PRESENT’S OFFICE, REGIONAL ADMINISTRATION
AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
CHEMISTRY FORM FOUR
MID-TERM EXAMS – AUG/SEPT – 2024
TIME: 2:30 HRS
INSTRUCTIONS
SECTION A
Answer all questions in this section
H2SO4(aq) H+ (aq) + SO42- (aq). From the equation, how many ions are there in 9.8g of H2SO4?
the forward reaction is exothermic. Which change would increase the production of Sulphur trioxide at equilibrium?
LISTA | LISTB |
|
|
SECTION B (54 marks)
Answer all questions in this section
(b) What is so called the universal solvent comment on this statement
4. Chemistry teacher guided students of form four to study carefully an experiment carried out in order to distinguish various substances formed during an experiment. The procedures were as follows
5. Mwasiti was supplied with two beakers, one containing 0.1M KOH standard solution, and the other beaker containing sulphuric acid solution whose molarity was not known. She was asked to find the molarity of the acidic solution. Mwasiti took the basic solution and put it into the burette, then she measured accurately 25cm3 of sulphuric acid using a measuring cylinder and transferred it into a conical flask, she is then added few drops of methyl orange indicator.
Her titration results were showing that 25cm3 of acid required 2cm3 of KOH standard solution.
She used the following formula to calculate the molarity of the sulphuric acid.
Molarity of H2SO4 acid = (Volume of acid x Volume of base)/Molarity of base
(a) What are the mistakes Mwasiti performed in her titration? (Four mistake).
(b) For each mistake, suggest the correct measure you would take.
6. (a) A person suffering from in digest ion produces1.0Litre of gastric juices per day which contains about 2.0g of hydrochloric acid. How many antacid tablets each containing 400mmg of sodium bicarbonate (NaHco3) is needed to neutralize all the hydrochloric acid produced in a day?
7. Explain how the following factors affect the rate of chemical reaction
8. During electrolysis of an aqueous of salt of metal X, a current of 2.0A was passed for 26 minutes and 32 seconds. The mass of metal ‘X’ deposited was 0.24g.
Answeronlytwo(02) questionsfromthissection.
9. Agriculture is back bone of our economy but the addition of in organic fertilizers in the farm is not as important as addition of organic manure. Discuss the correctness of this statement in four points.
10. The extraction of metals has economic advantageous in Tanzania, but it’s still destructive to the environment. Illustrate three (3) environmental destructions may be caused by the process, and suggest three (3) control measure to problem.
11. (a)Name the process used to obtain an aqueous solution of ethanol from a sugar, for example Glucose (C6H12O6)
(b) States without further description, the method you would use to obtain a sample of reasonably pure ethanol from the aqueous solution, and indicate the physical properties to which this separation in based.
(c) Briefly explain the following chemical reaction which takes place when: -
FORM FOUR CHEMISTRY EXAM SERIES 192
FORM FOUR CHEMISTRY EXAM SERIES 192
PRESIDENT’S OFFICE, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES,
PRE- MOCK CHEMISTRY FORM FOUR
Time: 3Hours
Instructions
SECTION A.
2. Match the compound in LIST A with the correct way to identify it in LIST B and write the letter of the correct answer on sheet provided.
LIST A | LIST B |
|
|
SECTION B: 54 Marks
3(a) State two reasons why we use the non-luminous flame for heating in a laboratory instead of using the luminous flame.
(b) Chlorine has two isotopes with atomic mass 35 and X occurring in the ratio 3:1 respectively. The relative atomic (R.M.A) of chlorine is 35.5. Determine the value of X.
(c) In an experiment to electroplate iron with silver, current of 1 Ampere was passed through a silver solution of ions for 60 minutes.
(i) Give a reason why it is necessary to electroplate iron.
(ii) Calculate the mass of silver deposited on iron during the electroplating process. (Ag = 108, IF = 96500c)
4. (a) Calculate the volume of 0.6M sulphuric (VI) acid solution needed to neutralize 30cm3 of 0.2Mpotassium hydroxide.
(b) A state of equilibrium between dichromate (vi) and chromate ions is established as shown below
Cr₂O₇²⁻ (aq) + H₂O (l) ⇌ 2 CrO₄²⁻ (aq) + 2 H⁺ (aq)
Orange (Yellow)
i. What is meant by dynamic equilibrium?
ii. State and explain observation made, when a few pellets of Potassium Hydroxide are added to equilibrium mixture
(c ) The following reaction takes place in a closed system:
N₂(g) + 3H₂(g) ⇌ 2NH₃(g) ΔH = -92 kJ/mol
Consider the following scenarios:
Scenario 1: More nitrogen (N₂) gas is added to the system.
Scenario 2: The temperature of the system is decreased.
Scenario 3 A catalysts is added to the system.
For each scenario:
a) Predict the direction in which the equilibrium will shift (left, right, or no change). b) Explain your reasoning using the principles of chemical equilibrium and Le Chatelier's principle.
5. Use the diagram below to answer the questions that follow.
(a) Identify the substances labelled R, S, K and P (b) What is the function of the part labelled P?
(c) Write half equations at the electrodes.
(d) Why is molten sodium chloride used instead of sodium chloride solution?
(e) Why is calcium chloride added in the electrolysis of molten sodium chloride?
(f) How is the calcium eventually separated from the sodium?
(g) When sodium is left exposed in the air a white solid is formed but when sodium is burnt in oxygen, a yellow solid is formed. Explain this difference using equations.
6. Use the information in the table below to answer the questions that follow. The letters do not represent the actual symbols of the elements.
Element | Atomic number | Melting point 0C |
R | 11 | 97.8 |
S | 12 | 650.0 |
T | 15 | 44.0 |
U | 17 | -102.0 |
V | 18 | -189.0 |
W | 19 | 64.0 |
(a) Give a reason why the melting point of;
(i) S is higher than that of R.
(ii) V is lower than that of U. (b) How does the reactivity of W with chlorine compare with that of R with chlorine?
(c) When 0.30g or R was reacted with water 1600cm3 of gas was produced. Determine the relative atomic mass of R. (Molar gas volume = 24000cm3 r.t.p
(d) Give one use of element V.
(e) Draw a structure of the compound formed when S reacts with U.
(f) Compare the atomic radius of element S and V. Give a reason
7. (a) Hard water has both advantages and disadvantages. Give one advantage and one disadvantage of using hard water
(b) Using an equation, explain how addition of sodium carbonate is used to remove water hardness.
(c) Outline three importance of a chemical equation.
8. I. In an experiment, copper metal was heated in the air to form a black solid T. dilute Sulphuric (VI) acid was then added to solid T resulting to formation of solution W, after which Ammonia was then added to solution W drop wise till excess
(a) Identify solid T
(b)Write a chemical equation for the reaction leading to formation of solution W
(c) State the observations made when the ammonia solution was added to solution W dropwise till excess.
II. Substance A is a solid that does not conduct electricity at room temperature. However, when molten, it becomes a good electrical conductor.
Substance B is a solid with a high melting point and can conduct electricity in the solid state.
a) Suggest the likely types of bonding present in Substance A and Substance B.
b) Explain the differences in their electrical conductivity in both solid and molten/liquid states.
(c) An experiment is set up to electrolyze a concentrated solution of sodium bromide (NaBr).
i) Identify the products that would form at the cathode and anode.
ii) Explain your reasoning, including relevant half-equations.
iii) Describe any observable changes expected during the electrolysis process.
SECTION B: 30 MARKS
Answer any two questions
9.(a) What name is given to each of the following?
(i) Ability of a metal to be beaten/ hammered to a sheet
(ii)Force of attraction that holds two molecules together
(b) When 3.1g of Copper {II} Carbonate were heated in a crucible until no further change in mass, solid L and gas M were formed
(i) Identify solid L and gas M
(ii) Write a chemical equation for the reaction that occurred
(iii) Given Cu=64, C=12,O=16, calculate the mass of the solid L that was formed
10 (a) Give the name of the following processes.
(i) A hot saturated solution of copper (II) sulphate is cooled to form crystals of copper (II) sulphate.
(ii)A white powder is formed when concentrated sulphuric (V) acid is added to blue hydrated copper
(II) sulphate.
(b)Study the flow chart below and answer the questions that follow.
(i) Name substances: B, C, D, and Solid E
(ii) Write equations for the reactions in steps; III and V
(iii) Write the ionic equation for the reaction in step II.
(iv) State any two observations made in step I.
11. (a) Addition of inorganic fertilizers in the farm is not as important as addition of organic manure. Discuss the correctness of this statement in four (4) points
(b) Soil fertility and soil productivity are mistakenly used to mean the same concept. How do they differ from each other? Give five points
FORM FOUR CHEMISTRY EXAM SERIES 185
FORM FOUR CHEMISTRY EXAM SERIES 185
PRESIDENT’S OFFICE, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES,
MID TERM ONE – MARCH-2024
CHEMISTRY FORM FOUR
Time: 3Hours
Instructions
SECTION A.
Answer all questions in this section.
LIST A | LIST B |
|
|
SECTION B
54 MARKS
Answer all questions
Use le chateliers Principle, suggest how you would use temperature and pressure to obtain the highest production of ammonium in equilibrium
(b) The formation of methane from hydrogen and carbon monoxide can be represented by:
CO(g) +2H2g CH3OH DH= 91KJ.........
What mass of hydrogen would cause heat change of 91KJ?
(ii) Why do laboratory doors open outwards?
(b) State the use of following item in first aid
(b) You are provided with compound 22.2%Zuric, 11.6% Sulphur, and 22.3%. Oxygen and the rest water of Crystallization. Calculate the molecular formula of the compound if its molecular mass is 283.
(a) molarity of KOH
(b) Mass concentration of pure KOH
(b) Comment on the following statement
(i) Lithium has large size than beryllium
(ii) Sodium is smaller than Potassium
(c) gives any four ions whose electronic configuration resemble that of Neon.
Using the law state above, derive mathematical expression of Faradays first law of electrolysis.
(b) How many moles of electrons will be transferred is Zinc metal is produced by a current of 14.23A. Supplied for 8.0hrs.
SECTION C
30 MARKS
Answer 2 questions from this section.
(b) Write down the molecular structure and IUPAC names of the Isomer whose molecular structure is C4H10
(c) By naming reagent, stating conditions whenever possible using a balanced equation describe how Ethane could be converted into
(a) Identify Substance P, R, I, M, W, and S
(i) Dilute nitric acid and solid P
(ii) Formation of white precipitate with gas I and Lime water.
FORM FOUR CHEMISTRY EXAM SERIES 177
FORM FOUR CHEMISTRY EXAM SERIES 177
PRESENT’S OFFICE, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
CHEMISTRY FORM FOUR
MID-TERM EXAMS – AUGUST – 2023
032/1 CHEMISTRY 1
TIME: 3:00 Hours YEAR. 2023
Instructions
SECTION A: (16 Marks)
Answer all questions
Which of the following statement is true about this reaction?
2. Match the uses of apparatus in list A with the respective element in list B by writing the letter of the correct response besides the item number in the answer sheet provided
LIST A | LIST B |
i. Holding , heating and estimating the volume of liquids ii. Holding substances that are being weighed or observed iii. Holding chemicals and heating small portions of chemicals of liquid or solid form iv. Adding small volume of liquids reagents to an exact point during experiment v. Holding and measuring liquid during experiment vi. Measuring mass of chemicals in the laboratory |
|
SECTION B (54 Marks)
Answer all questions in this section
4, Juma was given two gas jars, one containing gas “X” and another one containing gas “Z” Gas “X” is used to prepare water gas in the laboratory and gas “Z” is used treating sewage plants
4. 16.8 g of impure potassium hydroxide was dissolved in distilled water to make 100 ml. 20mls of this solution required 28mls of 0.07M sulphuric acid to react. Calculate;
5. (a) A form three student performed two different experiments
Experiment I; Students dissolved one tea spoon of sugar in cold water
Experiment II: Students dissolved one tea spoon of sugar in hot water
By using the concept of collision theory explain in which experiment the sugar dissolved more quickly?
(b)You are provided with the following equilibrium reaction
What happens to the production of ammonia if
6. Samwel bought all necessary building materials as he wanted to build modern and expensive house for his mother, four months later he found that almost all nails and iron sheets have been rusted, unfortunately he has no any extra money to buy the new nails and iron sheets. As a chemist student what will you advise Samwel (Give two points)
(b) Suppose you are in a bus travelling for annual holiday, a bus driver went to the petrol station to fill fuel but he forget to switch off the bus engine, this caused explosion hence the fire started.
As a form four student
7. (a)What are the four stages for extraction of moderate reactive metals
(b) In certain areas iron can be extracted through blast furnace which involve different temperatures such as10000C, 7500C and 2500C in different stages
(c).What are the two environmental effects caused by extraction of metals
8. During manufacturing of Sulphuric acid, Sulphur trioxide gas is dissolved in concentrated sulphuric acid instead of dissolving it directly in water
SECTION C (30 Marks)
Answer only two questions from this section
9. Explain the term substitution reaction as applied in organic chemistry
(b)With the use of chemical tests differentiate between saturated hydrocarbons and unsaturated hydrocarbons.
(c). Write and name all isomers of pentane
10. The head master of Mtakuja secondary school advised an environmental master to use manure and fertilizers in order to improve the growth of trees and plant around the school .What are the significance of manure and fertilizers as per head masters advise.(Five points)
11. There are various environmental plans to be used in controlling the solid waste and soil pollution in Mbozi municipality. Advise accordingly to the effective plans to be taken in order to achieve such activities.( Five points)
FORM FOUR CHEMISTRY EXAM SERIES 163
FORM FOUR CHEMISTRY EXAM SERIES 163
PRESIDENT OFFICE REGIONAL ADMNISTRATION
AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
COMPETENCE BASED ASSEMENT
CHEMISTRY FORM FOUR
TERMINAL EXAMS MAY – 2023
032/1
CHEMISTRY
TIME: 3HOURS
INSTRUCTIONS
Atomic masses; H=1, O=16, Na=23, C=12, Cl=35.5, N=14, Zn=65, S=32,
Ca=40, Fe=56, Cu=64, Al=27
GMV at s.t.p = 22.4dm3, Avogadro’s number = 6.02 x 1023
1Faraday = 96500 coulomb 1 litre = 1dm3=1000cm3
SECTION (16 MARKS)
LIST A | LIST B |
|
|
SECTION B (54 MARKS)
Answer all questions from this section
(b)(i)Wit aid of a balanced chemical equation name the products formed when nitrates of potassium and zinc decompose by heat
(ii)Suggest why nitrates of zinc and potassium behave differently on heating
Mention characteristics which make the ashes to be used for heart burn relief
(ii)Give four compounds founds in the laboratory which show the same characteristic as ashes.
(b)How many ions are there in 6.82g of Al2(SO4)3
Sample | Observation with soap solution | Observation for boiled sample with soap |
| No lather | Lather |
| Lather | Lather |
| Lather | Lather |
| No lather | No lather |
(b)The reaction which produces methanol from carbon monoxide and hydrogen is represented by the equation
The reaction is carried out at high pressure to give a better yield of methanol.
SECTION C (30 MARKS)
Answer only two (2) questions from this section,
(b)Define the following terms and give one example in each case
Then gas B is passed through water and finaly to concentrated
Sulphuric acid.
FORM FOUR CHEMISTRY EXAM SERIES 149
FORM FOUR CHEMISTRY EXAM SERIES 149
PRESIDENT OFFICE REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
COMPETENCE BASED ASSESSMENT
NEW EXAM FORMAT-2023
032/1 CHEMISTRY FORM FOUR
MID-TERM EXAMS MARCH – 2023
Time: 3:00 Hours
Instructions
SECTION A (16 marks)
Answer All Questions
1. For each of items (i) – (x), Choose the correct answer from the alternatives and write its letter beside the item number in answer sheet provided
2. Match the properties of element in List A with respective elements in List B by writing the letter of correct response besides item number in answer sheet provided
LIST A | LIST B |
|
|
SECTION B (54 Marks)
Answer all questions in this section
3. (a) The modern Periodic table law is based on modification of Mendeleev Periodic law. Explain the two theories differ from each other.
(b) Comment on the following statement
(c) Give four ions whose electron configuration resembles that of Neon
4. (a) Mr. Mwabashi asked student to prepare all requirements for extraction of sodium metal. Help them describe the use of each of the following
(i) Calcium Chloride (ii)Graphite rod (iii) Steel gauze
(b) Why is sodium collected upward in down cell?
(c) Write electrodes reaction is down cell during extraction of sodium
5. A solution contains 40.3g of substance XOH per liter 250.0cm3 of this solution required 30.0cm3 of 0.3M sulphuric acid for complete neutralization
6. (a) Differentiate alkanes from alkenes
(b) Study the flow chart below and answer questions that follow;
7. (a)A mass of 1.24g of a divalent metal was deposited when a current of 6A was passed through a solution of metal sulphate for 12minutes. Determine the relative atomic mass of the metal (1F = 96,500C)
(b)State two application of Electrolysis
8.(a) What is an alkali?
(b) Aqueous solution of 2M electronic acid and 2m nitric (v) acid were tested for electronic conductivity. Which solution is a better conductor of electricity? Explain
(c) Explain why it is not advisable to prepare a sample of carbon dioxide using barium carbonate and dilute Sulphuric (VI) acid
SECTION C (30 Marks)
Answer any two questions in this section
9. (a) What is Isomerism?
(b) Using illustration differentiate chain Isomerism from position Isomerism
(c) Alkenes are saturated, why alkenes are unsaturated explain
10. (a)Explain the following terms
(b)The industrial Oxidation of sulphur dioxide is summarized as follows
2So2(g) + O2(g) → 2SO3(g) DH= -94.9 KJ/Mol
What will be the effect of each of the following on production of sulphur Trioxide?
(c)Briefly explain how each of the following factors affects the rate of a chemical reaction
(d) Give one good reason for the following
11. (a)Using Iron filling, describe an experiment that can be conducted to show that Oxygen is present in air
(b)Element U has atomic number 12 while element V gas atomic number 16. How do the melting points of elements compare
(c) In haber process, nitrogen reacts with hydrogen according to the following equation;
3H2(g) + N2(g) → 2NH3(g) DH= -92KJ/Mol
FORM FOUR CHEMISTRY EXAM SERIES 141
FORM FOUR CHEMISTRY EXAM SERIES 141
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCY BASED SECONDARY EXAMINATION SERIES
CHEMISTRY FORM FOUR
TIME: 2 HOURS NOVEMBER 2022
INSTRUCTIONS:
1. This paper consists of sections A, B and C
2. Answer all questions in section A and B and only one (01) question from section C
3. Cellular phones and all programmable calculators are not allowed in the examination room
4. Write your examination Number on every page of your answer booklet(s)
5. The following constants may be used
1 Faraday = 96500 coulombs
G.M.V at stp = 22.4dm 3
Avogadro's number = 6.02 x 10 23 particles per mole Atomic masses
H = 1, C = 12, O = 16, Na = 23, S = 32, cU = 64, Ag = 108, Zn = 65
SECTION A: (15 MARKS)
Answer all questions in this section
1. For each of the items (i) — (x), choose the most correct answer from among the given alternatives and write its letter in the space provided
(i) The lead in a pencil is made of a mixture of graphite and clay. When the percentage of graphite is increased, the pencil moves across the paper move easily. Which statement explain this observation?
A. Graphite has high melting point
B. Graphite is a lubricant
C. Graphite is the form of carbon
D. Graphite is a non — metal
E. Graphite is a good conductor of electricity
(ii) Which process is used to convert calcium carbonate into calcium oxide
A. Electrolysis
B. Fractional distillation
C. Cracking
D. Thermal decomposition
E. Evaporation
(iii) One of the following substance is commonly used to determine the arrangement of metals in order or reactivity
A. Water
B. Salt
C. Acid
D. Base
E. Non -metal
(iv)The hottest part of a non - luminous flame is the region of
A. Green or blue zone
B. Purple or blue zone
C. Colourless inner zone
D. Thin outer zone
E. Blue zone
(v) The following are the properties of a good fuel except
A. Average value of velocity or combustion
B. High ignition point
C. Highest energy value
D. Environmental friends
E. Less or no waste products
(vi) A sodium atom (Na) and a sodium iron (Na+) have the same
A. Atomic site
B. Electronic configuration
C. Physical properties
D. Physical properties
E. Number of protons
(vii)Factors in an experiment that remain unchanged throughout the experiment is known as
A. Controlled variable
B. Dependent variable
C. Independent variable
D. Uncontrolled variable
E. Fixed factor
(viii) Coal, methane and hydrogen are burned as fuel, which description of this process is correct?
What happens to the fuel | Type of reaction |
| Endothermic Exothermic Endothermic Exothermic Displacement |
(ix)Petroleum is a mixture of different hydrocarbons, which process is used to separate petroleum into groups of similar hydrocarbons?
A. Combustion
B. Cracking
C. Fractional distillation
D. Reduction
E. Isomerism
(x) A car releases 5g of carbondioxide gas into air for each mile driven. The number of carbondioxide molecules released are
A. 1.0 x 1023
B. 6.8 x 1023
C. 6.3 x 1023
D. 5.8 x 1022
E. 6.8 x 1022
2. Match the item in LIST A with a correct response in LIST B by writing the letter of tie correct response below the corresponding item in the table Given
LIST A | LIST B |
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|
SECTION B: (70 MARKS)
Answer all questions in this section
3. (a) Element Q has 17 electron and 18 neutrons (i) What is the atomic number of element Q
(ii) What is the mass number of element Q
(iii) Write down the electronic configuration of element Q
(iv) In which group and period in the periodic table does element Q occupy?
(b)Given the following 204J 208 K 207L and AM are isotopes of element H, whose abundances are 2%, 24%, 22% and X% respectively. Calculate the abundance X% and the mass number A of isotope M, given that the atomic mass of element H is 207.
4. (a) State any three main physical properties of water and show the usefulness of each property.
(b)The following methods were used to soften 25cm 3 of the original sample of water. At the end of each experiment, the resultant product was treated with soap solution until lather was obtained
Method used | Volume required for 25cm3 0f product |
Filtering | 20 |
Distilling. | 1 |
Adding Na2CO3 washing soda | 1 |
Boiling | 20 |
Adding zeolite | 1 |
(i) Which methods were most suitable for softening hard water?
(ii) Which type of hardness was present in the sample provided? Explain
(iii) Which substances caused the hardness in the sample water?
(iv) Why did distillation and filtration produce such different results?
5. (a) Outline three reasons to explain why carbondioxide is used to extinguish fire
(b)A sample of mass 28.6g of hydrated sodium carbonate (Na2 C03. 101420) was heated such that water was entirely absorbed by 32g of anhydrous copper (Il) sulphate to form a blue compound of hydrated copper (Il) sulphate (CUS04 . XH20). Find the value of x in the copper (Il) sulphate
6. (a) Complete and balance the following chemical equation.
(b) Write down the condensed structural isomers of alcohol of molecular formula C4H100
7. (a) By using two examples in each case, categorize fuel according to their physical state
(b) What is the simplest chemical formula of a compound formed when 36g of magnesium combine with 14g of nitrogen?
8. (a) Complete the following table
Element | When burned forms | Kind of oxide | Action of oxidation water | Action on litmus |
Carbon | Co2 |
|
|
|
Sodium |
|
| NaoH |
|
Sulphur |
| Acidic |
| Blue to red |
(b) Using calcium oxide and carbon dioxide explain the meaning of
(i) Acidic oxide (ii) Basic oxide
9. A piece of marble chips (calcium carbonate) was placed in a beaker containing an excess of hydrochloric acid standing on a reading balance. The mass of the beaker and its contents were recorded after eve 2 minutes as shown in the diagram below
(a) Why was there a loss of mass?
(b) Write the equation for the reaction above
(c) State three (3) different ways in which reaction could have been more rapid
(d) Why did the mass remain constant after 10 minutes?
10. (a) Nowadays the use of spatula which are made of iron is discouraged in the laboratory. Explain one reason for the scenario.
(b) Write a chemical composition for the following fire extinguisher
(i) Dry powder (ii) Wet chemical
(c) How can you prevent the following iron materials from rusting?
(i) Gates
(ii) Bicycle chain
(iii) Iron sheets
11. (a) How can a mixture of two or more miscible liquids be separated from one another?
(b) Make a flow chart to show the separation of a mixture of common salt and sand
12. Four experiment were conducted using chemicals P, Q, L and M on different materials.
The results were given as indicated below. You are required to write the correct terminology which suits each of the results below and give precautions of handling the warning signs which goes with it.
(i) When chemical P was poured on the wood it completely damage the surface of the wood
(ii) When chemical Q was poured on the small fire, it found burst and turning a bigger fire
(iii)When chemical L was swallowed by a rat, the rat died immediately
(iv)When chemical M was exposed on air sudden blast accompanied with light occurred (b) Give one main importance of chemical warning signs
SECTION C: (15 MARKS)
13. (a) State Faraday's first law of electrolysis
(b)The apparatus shown below was used in the experiment of electroplating a key with silver. The electrolyte used is silver nitrate and an electric current of 15A was passed in the electrolyte for two and half hours. Study it carefully and answer the questions that follows;
(i) Name the process taking place on key as either oxidation or reduction
(ii) With the current of 15A, what mass of silver was deposited on the key?
(iii) Name the gas formed at the anode
(iv) Name the acid formed as a result of electrolyzing silver nitrate
(v) What volume of the named gas in (iii) above was collected in this experiment?
14. (a) Eutrophication is excessive growth of aquatic plant and algae in water bodies (i) Give two causes of eutrophication
(ii) Explain the effect of eutrophication. (Give two points)
(b)Explain how industrial workers can be protected against harmful effect of the chemicals. (Give three points)
FORM FOUR CHEMISTRY EXAM SERIES 129
FORM FOUR CHEMISTRY EXAM SERIES 129
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCY BASED SECONDARY EXAMINATION SERIES
CHEMISTRY
FORM FOUR- SEPT 2022
CODE 032/1
INSTRUCTIONS
Atomic masses H=1, C=12 , N=14, O=16 , Cl=35.5 , CU=64 , P=15, Fe=56
Avogadro’s number =6.02 x 1023.
GMV at s.t.p= 22.4 dm3.
1 Faraday = 96,500 coulombs.
Standard pressure =760 mm Hg.
Standard temperature =273 K.
1 litre = 1 dm3 =1000 cm3.
SECTION A (15 Marks)
Answer all questions in this section
2. Match the properties of element in list A with the respective element in List B by writing the letter of the correct response besides the item number in answer sheet provided.
LIST A | LIST B |
(i) A black solid element which burns with reddish glow giving off colorless gas which is slightly acidic (ii) Silvery white metal which burns with golden yellow flame giving an oxide which is basic in nature (iii)A yellow element in color which burns with blue flame giving colorless gas which is strong acidic in nature (iv) A shinning white strip metal burns with dazzling white flame giving an oxide which is slightly basic in nature (v) A silvery white metal which burns with brick red giving off oxide which is white solid
|
|
3. (a) The Modem periodic law is based on modification of Mendeleev periodic law. Explain how the two theories differ from each other.
(b) Comment on the following statement
(i) Lithium has large size than Beryllium
(ii) Sodium is smaller than potassium
(c) Give any four ions whose electronic configuration resemble to that of Neon. (07 Marks)
4. a) How many chlorine molecules are in 20cm3 of chlorine gas at s.t.p.
b) Calculate number of ions present in 5g of copper (II) Nitrate
5. (a) (i) People suffering from heart burn usually use wood ashes for relief. Mention chacteritics which makes the ashes to be used for heart burn relief.
(ii) Give four compounds found in the laboratory which show the same characteristic as ashes.
(b) How many ions are there in 6.82g of Al2(SO4)3
6. 5.3g of X2CO3 was dissolved in water to make 0.5 litre of a solution. 25cm³ 0f this solution required 50.0cm³ of 0.1M HCl for complete neutralization.
a) Write the balanced chemical equation for the reaction
b) Calculate the concentration of X2CO3 in mol/dm3
c) Calculate the relative molecular mass of X2CO3
d) Calculate the relative atomic mass of X
e) What is the name and symbol of element X
7. (a) A gaseous compound consists of 86% Carbon and 14% Hydrogen by mass. At S.T.P, 3.2dm3 of the compound had mass of 6g.
(i) Calculate its molecular formula
(ii)Give the IUPAC name of the compound
(b) Most of the apparatus in the laboratory are made up of glass materials. Support this statement by giving ant two (2) reasons. (07 Marks)
8. Element R having atomic number 20 combines with element S having atomic number 17 to form a certain compound
a) Write the formula of the compound and state the type of bond formed in the compound
b) Give any three properties of the compound formed in 7(a) above
9. a) Muumini is a student from Katosani secondary school, she is not able to State Le Chatellier’s principle, Help her.
b) In the industrial preparation of Sulphur trioxide mr Atieno yo established equilibrium between Sulphur dioxide and oxygen gas as follows:
2SO2(g) + O2(g) 2SO3(g)∆H= - 94.9KJ/mol.
i. How would you adjust temperature and pressure to maximize the proportion of the product at equilibrium?
ii. Why is it unfavorable to work with very high pressure and very low temperature in the contact process?
iii. What catalyst is used to speed up the rate of formation of Sulphur trioxide before attaining the equilibrium?
10. a) Mr Mapulishi tasked to prepare all requirements for extraction of sodium.Describe the use of each of the following during extraction of Sodium
i. Calcium Chloride ii. Graphite anode
iii. Steel gauze
b) .Why sodium is collected by upwards in the downs cell
c) Write electrodes reaction in downs cell during extraction of Sodium
11. Mr Kalubandika wanted to know some chemistry pertaining concepts. Help Mr Kalubandika to answer the following conceptual questions.
a) In which other areas do we find the warning signs out of laboratory (give four point)
b) Explain how measurements of volume differ when using measuring cylinder and burette
c) It is recommend that laboratory apparatus should be properly washed or wiped after use, explain the significance for this when
i. Measuring volume of liquids
ii. Measuring mass of substance
12. (a) Give the meaning of the following terms
(i) Soil pH (ii) Liming
(b) (i) Explain why sulphur and its compounds are removed from the fuel before they are burned
(ii) By using a reaction equation explain how propane differs from propene
13. (a) Outline any three uses of carbon dioxide gas in animals and plants
(b) Complete the following reactions
(i) CH2=CH2 + O2
(ii) CaC2 + 2H2O
(iii)CH4 +Cl2
(iv) C2H5OH +O2
14. In q certain chemical plant that deals with the production of hydrogen gas, a certain chemist passes an electric current in series through copper (II) Sulphate and sulphuric acid solutions. In both electrolytes, inert electrodes were used. If 8400cm3 of hydrogen at S.T.P were produced for several hours, what volume of oxygen gas would also be produced? What mass of copper was produced?
FORM FOUR CHEMISTRY EXAM SERIES 119
FORM FOUR CHEMISTRY EXAM SERIES 119
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCY BASED SECONDARY EXAMINATION SERIES
CHEMISTRY -SEPT 2022
FORM FOUR
CODE 032/1
CHEMISTRY 1
TIME:3HOURS SEPT 2022
INSTRUCTIONS
Atomic masses H = 1, O = 16, S = 32, Zn = 65, Fe = 56, Cu = 64, Ca = 40.
Avogadro’s number = 6.02 1023
GMV at s.t.p = 22.4dm3
1 Faraday = 96500 coulombs
1Litre = 1dm3 = 1000cm3
SECTION A (15 Marks)
Answer all questions in this section
( c)Lemon juice, PH 5 (d)Salt water, PH 7
( e)Orange juice PH 4
ZnCO3(s) + 2HCl(aq) → ZnCl2(aq) + CO2(g) + H2O(l)
What volume of carbon dioxide gas is produced at S.T.Pto form 0.1 mole of the acid?
Before After
What type of reaction took place above?
( c)Neutralization (d)Reduction reaction (e)Resolution reaction
(c)Manufacture of margarine (d)Formation of water (e)As rocket fuel
Which of these statements are correct?
(d)1 and 2 only (e) 3 and 2 only
(c)Has a sour taste (d)Turns a blue litmus paper red
(e)Does not react with base
LIST A | LIST B |
|
|
SECTION B (70 Marks)
Answer all questions from this section
(ii) In the following reaction state the substance which is reducing agenda and oxidizing agent.
H2 (g) +CuO(S) → Cu (g) +H2O (l)
(b) Classify the following reaction into oxidation and reduction reaction.
(ii) Fe2+(aq)+ e → Fe3+(aq)
(iii) S(s) + O2(g) → SO2(g)
(iv) N2(g) + 3H2(g) → 2NH3(g) (7 marks)
H2SO4 (aq) + Ca(OH)2(aq) → CaSO4(aq) + H2O(l)
(b) State three conditions necessary for rusting to occur.(7marks)
(b) Explain how the knowledge of chemistry is applied in the following field.
(i) Pharmacy (ii) agriculture (7marks)
(b) Give out the role of the following chemicals in water treatment and purification.
(b) In volumetric analysis not all reactions are suitable for titration. Give out three conditions necessary for titration. (7 marks)
(b) 0.4 faradays of electricity were passed through solutions of copper (II) sulpahete and dilute sulphuric acid. Calculate the volume of hydrogen gas produced at S.T.P.(7amrks)
(b) Write all possible isomers of (C5H8).(7marks)
(b) Draw the warning sign that should be put to the container caring the following chemicals.
(i) Concentrated sulphuric acid.
(ii) Zinc sulphate crystals (7marks)
SECTION C (15Marks)
Answer only one question from this section
1 | Page
FORM FOUR CHEMISTRY EXAM SERIES 113
FORM FOUR CHEMISTRY EXAM SERIES 113
THE PRESIDENT’S OFFICE
MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCE BASED SECONDARY EXAMINATION SERIES
CHEMISTRY TERMINAL EXAMINATION
FORM FOUR-2022
Time: 3Hours
Instructions.
Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4dm3
1 faraday = 96,500 coulombs.
Standard temperature = 273K
Standard pressure = 760mmHg.
1 Litre = 1 dm3 = 1000cm3
SECTION A ( 15 Marks)
Answer all questions in this section
1. For each of the items (i)-(x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
List a | List b |
|
|
SECTION B (70 marks)
Answer all questions in this section
(ii) Write two balanced equations for the above reactions
(b) When crystals of hydrated sodium carbonate (Na2CO3xH2O) where heated strongly only 37.06% by weight of the salt remained. How can you show that the value of x in Na2CO3 .xH2O is 10?
Study the flow chart below and answer questions that follows.
(b) Draw an energy level diagram for the decomposition of potassium chlorate when a catalyst: (i) is used (ii) not used
6. (a) Briefly explain the concept of scientific procedure.
(b) What is the importance of the scientific procedure in daily life? Give two points.(7 marks)
7. Study the information in the table below and answer the questions that follow;
Element | Atomic number | Boiling point |
A | 3 | 1603 |
B | 13 | 2743 |
C | 16 | 718 |
D | 18 | 87 |
E | 19 | 1047 |
8(a) Why is a fertile soil not necessarily productive?-give 2 points.
(b)(i) why is liming material added to soil?
(ii) What are the causes that make the soil in need of liming material?-give 2 points.
9(a) Why do iron window frames rust quickly even though they are painted while aluminium frames are resistant to rusting?
(b)Why are aluminium vessels used to transport nitric but not sulphuric acid?
10(a) (i) What is meant by fuel?
(ii) How many classes of fuels are there?
(b)(i) The traditional process of making charcoal in an earth mould or pit kiln is wasteful process. Briefly explain.
ii)what is the effect of using charcoal on the environment?
11(a) (i) What is the relationship between athanoic acid and ethanol?
(ii) How does the acidity of ethanoic differ to that of sulphuric acid?
(b)How does ethanoic acid react with:- (i)sodium metal? (ii) sodium carbonate solution?
SECTION C (15 MARKS)
Answer all question in this section.
12. During electrolysis one ion is discharged at each electrode. When two or more ion of similar charge are present in an electrolyte, only one ion is selected for discharge.
The selection depends on different factors. Explain how these factors affect the selection. Giving examples and relevant equations in each case.
13.You are in Amboni district in Tanga region where there is potential sulphur deposit. The district development society aims to extract the sulphur and has come to you for advice. Explain to the society.
13. (a) Give three ways in which environmental destruction is likely to occur during extraction of metals.
(b) The following equations represent the steps involved in the conversion stages of iron extraction in Bussener converter. Arrange the equations in chronological order from the first step to the last by writing the respective letter so as to get a complete explanation of the conversion stage.
V: 2Cu20(S) + Cu2S(S)→ 6Cu (l) + S02 (g)
W: FeO (l) + SiO2(g) → FeSiO3
X: 2Cus(s) +302 (g) → 2Cu20(s) +2S02 (g)
Y: 2FeS (l) +302 (g) → 2Feo(1) + 2S02 (g)
1
14. Using a well labelled diagram, explain how sulphur is extracted using the Frasch process
FORM FOUR CHEMISTRY EXAM SERIES 88
FORM FOUR CHEMISTRY EXAM SERIES 88
THE PRESIDENT’S OFFICE
MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCE BASED SECONDARY EXAMINATION SERIES
CHEMISTRY MID TERM EXAMINATION
FORM FOUR-MARCH/APRIL-2022
Time: 3Hours
Instructions.
Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4dm3
1 faraday = 96,500 coulombs.
Standard temperature = 273K
Standard pressure = 760mmHg.
1 Litre = 1 dm3 = 1000cm3
SECTION A (15 Marks)
Answer All questions in this section.
B 2C12(g) + 2H20(1)→ 4C1-1(aq) + 02(g) + 2H2(s)
v. Which is not true about hydrogen chloride?
A. Magnesium sulphate
B. Sodium chloride
C. Calcium sulphate
D. Magnesium chloride
a. Ca(HCO3)2(aq) → CaCO3(g) + H2O(l) + CO2(g)
b. Ca(HO)2(aq) + Ca(HCO3)2(aq) → CaCO3(g) + 2H2O(l)
c. Ca2+(aq) + CO2-(aq) → CaCO3(g)
d. Ca2+(aq) + Na2Z(aq) → 2Na+(aq) + CaZ(g)
A. Calcium carbonate
B. Calcium chloride
C. Sodium carbonate
D. Magnesium sulphate
E. Calcium hydrogen carbonate
A. a and b
B. b and c
C. c and d
D. d and a.
A. Ca(HCO3)2, Mg(HCO3)2
B. CaCl2, MgSO4
C. Fe(NO3), Ca(NO3)2
D. mgCl2, FeCl2
2. Match the physical processes represented by arrows (i) - (v) in List A with the corresponding terms in List B by writing the letter of the correct response beside the item number in the answer booklet provided.
LIST A | LIST B |
i) Water that easily forms lather with soap ii) Water that does not form lather with soap iii) Water that contains dissolved calcium and magnesium hydrogen carbonate iv) Water that contains dissolved sulphates of calcium and magnesium v) An element whose complex ion is used in softening water
| A. Plaster of Paris B. Gypsum C. Nitrogen dioxide D. Carbon dioxide E. Calcium F. Phosphorous G. Soft water H. Hard water I. Permanent hard water J. Temporary hard water K. Scum L. Stain M. Fur N. Coating O. Sodium P. Potassium Q. magnesium |
3. Figure 1 below represents the laboratory preparation of hydrogen chloride gas.
(a) Name the parts labelled A, B, C and D.
(b) (i) Do you think the gas can be collected over water? Give reasons for your answer.
(c) Write chemical equations for the reaction between:
(i) Ammonia gas and hydrogen chloride.
(ii) Hydrogen chloride gas and water.
4. Write equation for reaction between
5. Explain what happens when a stream of Hydrogen chloride gas is passed over
6. Study the diagram below and answer the questions that follow
The apparatus above are used to prepare chlorine
Y
X
P
7. Write down the chemical equations used when softening water of the
(a) Temporary hardness through (i) boiling water (one question) (ii) use of chemicals (two equations)
(b) Permanent hardness through (i) use of chemicals (one equation) (ii) iron exchange (one equation)
8. Define the following terms;
(e) Soft water
(f) Hard water
(g) Permanent hardness of water (h) Temporary hardness of water
9. a) What is the hardness of water?
b) Briefly explain types of hard of water.
c) State the causes of hardness of water for each type mention in (b) above.
d) Explain how you would remove the hardness of water according to its type.
e) Give three (3) advantages and three (3) disadvantages of the hard water.
10. Balance the following equations:
(i)Ca + H3PO4→ Ca3(PO4)2 + H2
11. Give the name of the types of reaction represented by each of the following chemical equations.
(iii)Zn(s)+CuS04(aq) —>ZnSO4(aq) +CU(S)
12. Complete the following equations and determine the type of chemical reaction involved in each case.
(i) Zn(s)+ H2SO4(aq)→
(i) AgN 03(aq) + NaCl(aq)→
(iii) N2(g) + H2(g) →
FORM FOUR CHEMISTRY EXAM SERIES 74
FORM FOUR CHEMISTRY EXAM SERIES 74
THE UNITED REPUBLIC OF TANZANIA
PRESIDENT’S OFFICE
REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
FORM FOUR MID TERM EXAMINATION-2021
CHEMISTRY
Time 3:00 HrsAUG, 2021
Instructions
Atomic masses: H=1, O=16, S=32, Ca=40, Zn=65, Cl=35.5, Na=23, C=12, Ag=108 Avogadro’s number = 6.02 x 1023 GMV at s.t.p = 22.4dm3 1 faraday = 96,500 coulombs 1 litre = 1dm3 = 1000cm3 |
SECTION A (15Marks)
Answer all questions in this section
I 2(g) + H 2(g) 2HI (g)
The reaction is:-
Atmosphere is that it
LIST A | LIST B |
|
|
SECTION B (70Marks)
Answer all questions in this section
(b) Complete and balance the following chemical reaction
b) Calculate number of ions present in 5g of copper (II) Nitrate
b) In the industrial preparation of Sulphur trioxide equilibrium is established between Sulphurdioxide and oxygen gas as follows:
2SO2(g) + O2(g)⇋2SO3(g)∆H= - 94.9KJ/mol.
Use the above data to answer the following questions
ii. Calculate the value of X in the hydrated sodium carbonate.
b).Why sodium is collected by upwards in the downs cell
c). Write electrodes reaction in downs cell during extraction of Sodium
b) Explain how measurements of volume differ when using measuring cylinder and burette
c) It is recommend that laboratory apparatus should be properly washed or wiped after use, explain the significance for this when
b) State four industrial application of electrolysis
SECTION C (15 MARKS)
Answer one (1) question in this section
b) Write down the molecular structure and the IUPAC names of the isomer whose molecular structure is C4H10
c)By naming the reagents, stating the conditions whenever possible using a balances equation describe how ethane could be converted into
1
FORM FOUR CHEMISTRY EXAM SERIES 68
FORM FOUR CHEMISTRY EXAM SERIES 68
THE PRESIDENT’S OFFICE
MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCE BASED SECONDARY EXAMINATION SERIES
CHEMISTRY MID TERM EXAMINATION
FORM FOUR-AUG/SEPT 2021
Time: 3Hours
Instructions.
Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4dm3
1 faraday = 96,500 coulombs.
Standard temperature = 273K
Standard pressure = 760mmHg.
1 Litre = 1 dm3 = 1000cm3
SECTION A (15 Marks)
Answer All questions in this section.
1. For each of the items (i)-(xv), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) 1.4 g of potassium hydroxide is dissolved in water to form 250 cm3 of solution. What is the molarity of this solution?
(ii) In the blast furnace carbon monoxide is prepared by passing carbon dioxide over a redhot coke. Carbon dioxide is
(iii) Copper can be separated from a mixture of zinc and copper by adding to the mixture
(iv) 65.25 g sample of CuSO4.5H2O (M = 249.7) was dissolved in water to make 0.800 L of solution. What volume of this solution must be diluted with water to make 1.00 L of 0.100 M CuSO4?
(v) Which action should be taken immediately after concentrated sulphuric acid spilled on the skin?
(vi) The only metal which does not react with dilute hydrochloric acid is
(vii) 10 cm3 of 0.4 M sodium hydroxide are added to 40 cm3 of 0.2 M hydrochloric acid. The resulting mixture will be
(viii) The ionic equation when aqueous ammonium chloride reacts with sodium hydroxide solution is represented as:
(ix) The apparatus suitable for measuring specific volumes of liquids is called?
(x) The property of metal to be drawn into wires is called?
2.Match the physical processes represented by arrows (i) - (v) in List A with the corresponding terms in List B by writing the letter of the correct response beside the item number in the answer booklet provided.
LIST A | LIST B |
|
|
SECTION B (70 Marks)
Answer all questions in this section.
3. (a) How many chlorine molecules are in 20 cm of chlorine gas at s.t.p?
(b)Calculate the number of ions present in 5 g of copper II nitrate. (7 marks)
4. A solution contains 40.3g of substance XOH per litre .250.0cm3of this solution required 30.0cm3 of 0.3M sulphuric(VI)acid for complete neutralisation.
(a) Calculate the number of moles of XOH that reacted.
(b) Determine the relative atomic mass of X.
5. Sulphur(IV) oxide is prepared in the laboratory using the set-up in Figure 3.
Study it and answer the questions that follow.
(a) Identify substance F. (1 mark)
(b) Write an equation for the reaction that takes place in the flask. (1 mark)
(c) State the purpose of liquid G. (1 mark)
6. (a) A mass of 1.24g of a divalent metal was deposited when a current of 6A was passed through a solution of a metal sulphate for 12 minutes.Determine the relative atomic mass of the metal( Faraday = 96,500 C mol-1(3 mark)
(b) State two application s of electrolysis.
7. In the Haber process, nitrogen reacts with hydrogen according to the following equation.
3H2(g) + N2(g)→ 2NH3(g) ; AH = -92 kJ/ mol
(a) What would be the effect of adding a catalyst on the position of the equilibrium? (1 mark)
(b) Explain why it is not advisable to use temperatures higher than 773 K in the Haber process. (2 marks)
8. You are provided with solid potassium hydrogen carbonate. Describe how a solid sample of potassium nitrate can be prepared.
9. Study the set-up in Figure 6 and answer the questions that follow.
(a) Name the substance that was collected in tube P. (1 mark)
(b) Write an equation for the reaction which occurs in tube Q in the first few minutes of the experiment. (1 mark)
(c) Give a suitable conclusion for the experiment in the set-up. (1 mark)
10.W is a colourless aqueous solution with the following properties:
I It turns blue litmus paper red.
II On addition of cleaned magnesium ribbon, it gives off a gas that burns with a pop sound.
III On addition of powered sodium carbonate, it gives off a gas which forms a precipitate with calcium hydroxide solution.
IV When warmed with copper(II) oxide powder, a blue solution is obtained but no gas is given of
V On addition of aqueous barium chloride, a white precipitate is obtained.
(a) (i) State what properties (I) and (III) indicate about the nature of W. ( I mark)
(ii) Give the identity of W. (l mark)
(iii) Name the colourless solution formed in (II) and (III). (2 marks)
(iv) Write an ionic equation for the reaction indicated in (V). ( I mark)
11. (a) 20 cm3 of a solution containing 7 g dm-3 of sodium hydroxide were exactly neutralized by 25 cm3 of 0.10 M hydrochloric acid. Calculate the concentration of sodium hydroxide in moles per dm3.
(b) (i) Write the reaction equations involved in the industrial manufacturing of sulphuric acid starting with sulphur dioxide in the contact process.
(ii) Explain why sulphur trioxide is not dissolved directly in water to obtain sulphuric acid in contact process.
12. (a) In the blast furnace, iron ore can be reduced using coke at a temperature of about 1300°C.
(i) Write an equation for the exothermic reaction that causes this high temperature.
(ii) State how carbon monoxide is formed.
(iii) Write a word equation for the formation of slag.
12. (b) Consider elements with atomic number 1, 11, 12 and 17.
(i) What are the types of oxides formed by elements with atomic number 11 and 12?
(ii) Write an equation which represents a reaction between the element with atomic number 1 and 17.
(iii) Write a balanced chemical equation between the oxide of the element with atomic number 11 and aqueous solution of the compound formed in 4 (a) (ii).
SECTION C (15 Marks)
Answer one (1) question in this section.
13. Explain five methods to prevent terrestrial pollution.
14. (a) A current of 0.5 A were made to flow through silver voltameter for 30 minutes. Calculate the mass of silver deposited and the equivalent weight of silver.
(b) Explain the following reactions giving one example in each:
(i) Addition reaction.
(ii)Elimination reaction.
FORM FOUR CHEMISTRY EXAM SERIES 58
FORM FOUR CHEMISTRY EXAM SERIES 58
THE PRESIDENT’S OFFICE
MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCE BASED SECONDARY EXAMINATION SERIES
CHEMISTRYTERMINALEXAMINATION
FORM FOUR-2021
Time: 3Hours
Instructions.
Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4dm3
1 faraday = 96,500 coulombs.
Standard temperature = 273K
Standard pressure = 760mmHg.
1 Litre = 1 dm3 = 1000cm3
SECTION A (20 Marks)
Answer All questions in this section.
1. For each of the items (i)-(xv), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) Which one of the following sets of laboratory apparatus are used for measure volume?
(ii) The empirical formula of certain compound in CH3. Its molar mass is 30 g. What will be its molecular formular?
(iii) In order to produce the greatest amount of hydrogen in a short time, one gram of magnesium ribbon should react with
(iv) Fractional distillation process of a mixture of water and ethanol is possible because
(v) Which of the following substances represent a group of acidic oxides?
(vi) What will the molarity of a solution which contains 26.5 g of anhydrous sodium carbonate in 5 dm3 of solution?
(vii) The Brownian movement is taken to be the evidence of the:
(viii) One off the isotopes of an element X has an atomic number Z and a mass number A. What is the number of neutrons contained in the nucleus of the element X?
(ix) C2H4Cl can be represented in different structures which are called
(x) _____ is the general term used to explain a mixture of different metals.
LIST A | LIST B |
|
|
SECTION B (70 Marks)
Answer all questions in this section.
3.A Form Three student conducted an experiment to prepare a gas in the laboratory by decomposing a certain compound using electricity. She allowed a steady electric current to flow through the solution for 3 hours at s.t.p. If the volume of the gas obtained was 4.12 dm3 and the gas relighted a glowing splint;
(a)name the gas that was produced.
(b)calculate the electric current that was flowing in the solution.
4. (a)An atom M has an atomic number 14 and mass number 28.
(i)What is the number of protons and neutrons?
(ii) Write the electronic configuration of atom M.
(b) Calculate the volume of water which was produced when 1,120 cm3 of oxygen at s.t.p. was liberated during the decomposition of hydrogen peroxide. The density of water = 1.0 g/cm3
5. An experiment was carried out to prepare crystals of magnesium sulphate.
Excess magnesium powder was added to l00cm'of dilute sulphuric(VI) acid in a beaker and warmed until no further reaction took place.
The mixture was filtered and the filtrate evaporated to saturation, then left to cool for crystals to form.
(a) (i) Write an equation for the reaction.
(ii) Explain why excess magnesium powder was used.
(iii) State how completion of the reaction was determined.
(iv) What is meant by a saturated solution?
(v) Explain why the filtrate was not evaporated to dryness.
6. (a) The diagram in Figure 4 was used to prepare hydrogen chloride gas which was passed over heated iron powder.
(i) Give a pair of reagents that will produce hydrogen chloride gas in flask A.
(ii) Name the substance in flask B.
(iii) State the observation made in the combustion tube.
(iv) Write an equation for the reaction in the combustion tube.
(v) Describe a chemical test for hydrogen chloride gas.
(b) (i) Identify the gas that bums at the jet.
(ii) Explain why the gas in (b) (i) is burned.
(b) Write an equation for the complete combustion of ethane.
(c) Give reasons why excess hydrogen chloride gas is dissolved using the funnel arrangement.
(d) State what will be observed when the reaction in the combustion tube is complete.
7. The set-up in Figure 2 was used to prepare a sample of ethane gas. Study it and answer the questions that follow.
(a) Name B - sodium propanoate/:
(b) Write an equation for the complete combustion of ethane.
(c) State one use of ethane.
8. (a) A sample of water is suspected to contain sulphate ions. Describe an experiment that can be carried out to determine the presence of sulphate ions.
(b) State one characteristic of a reaction where equilibrium has been attained.
9. Copper(II) ions react with excess aqueous ammonia to form a complex ion.
(a) (i) Write an equation for the reaction that forms the complex ion.
(ii) Name the complex ion.
(b) Explain why CH4is not acidic while HCl is acidic yet both compounds contain hydrogen.
10. The flow chart in Figure 3 shows the process of obtaining a sample of nitrogen gas. Study it and answer the questions that follow.
(a) Identify X (I mark)
(b) Write an equation for the reaction with heated copper turnings.
(c) Name an impurity in the sample of nitrogen gas.
11. Study the flow chart in Figure 5 and answer the questions that follow.
(a) Identify substances K and L. K:
(b) Name one reagent that can be used to carry out process J.
FORM FOUR CHEMISTRY EXAM SERIES 48
FORM FOUR CHEMISTRY EXAM SERIES 48
THE PRESIDENT’S OFFICE
MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
CHEMISTRY 1 MID TERM EXAMINATION
FORM FOUR-2021
Time: 3Hours
Instructions.
Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4dm3
1 faraday = 96,500 coulombs.
Standard temperature = 273K
Standard pressure = 760mmHg.
1 Litre = 1 dm3 = 1000cm3
SECTION A (20 Marks)
Answer All questions in this section.
1. For each of the items (i)-(xv), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
2. (a) Match the items from list A with those in list B.
LIST A | LIST B |
|
|
3. Figure 1 below represents the laboratory preparation of hydrogen chloride gas.
(a) Name the parts labelled A, B, C and D.
(b) (i) Do you think the gas can be collected over water? Give reasons for your answer.
(c) Write chemical equations for the reaction between:
(i) Ammonia gas and hydrogen chloride.
(ii) Hydrogen chloride gas and water.
4. (a) 1.4gm of potassium hydroxide is dissolved in water to form 250m3 of solution. What is the
molarity of this solution?
(b) What is the molar concentration of a solution containing 1.75 moles of the solute in 3
litres (dm3)?
5. (a) How many molar volumes of 132.0g of CO2 are there at STP?
(b) Determine the number of molecules in 0.25 moles of lead (II) nitrate.
6. (a) What mass in grams of hydrated sodium carbonate (Na2CO3 . 10H2O) in 65cm3 of 0.2M
solution?
(b) What volume of carbon dioxide would be evolved at STP when 6.2g of copper (II)
carbonate is reacted with Suphuric acid?
7. You are given the following symbols of metals’ Zn, Na, Cu, Ag, Mg
8. (a) Give the chemical formula for each of the following;
(b) Complete the following equations and balance them.
9. (a) What is meant by Dilution?
(b) Determine the litres of water that must be added to 30cm3 of 12M HCl to get a solution
which is exactly 0.25M.
10. (a) State two advantages of hard water.
(b) State two disadvantages of hard water.
(c) Give two methods of softening temporary hardness of water.
11. (a) Define the terms Molecular formula.
(b) Substance X contains 52.2% carbon, 13.0% hydrogen, the rest being oxygen. Calculate the empirical formula of X.
(c) If the density of X is 23, calculate the Molecular formula of X.
SECTION C: 15 MARKS
Answer the questions from this section and include the necessary details.
13. (a) (i) With the aid of a well labelled diagram, explain how you can prepare hydrogen gas
from the laboratory, using zinc metal and dilute hydrochloric acid.
(ii) Write a balanced chemical for the reaction taking place.
(b) (i) What is observed which hydrogen is passed over red hot copper (II) Oxide?
(ii) Write equation for the reaction that takes place in b(i) above.
(c) Which method would you use to prepare big crystals of sodium nitrate in the laboratory?
Explain briefly.
14. 25cm3 of potassium hydroxide were placed in a flask and a few drops of phenolphthalein indicator were added. Dilute hydrochloric acid was added until the indicator changed colour. It was found in the 21cm3 of acid were used.
From above information answer the following questions;
hydroxide solution?
(ii) What colour was the solution in the flask at the start of the titration?
(iii) What colour did it turn when the alkali had been neutralized?
(ii) Name the salt formed in the neutralization.
(iii) Write an equation for the reaction.
(iv) Is the salt, normal or acidic salt? Give reasons for your answer.
FORM FOUR CHEMISTRY EXAM SERIES 46
FORM FOUR CHEMISTRY EXAM SERIES 46
THE PRESIDENTS OFFICE
MINISTRY OF LOCAL GOVERNMENT AND REGIONAL ADMINISTRATION
MOTHLY SERIES EXAMINATIONS
JANUARY 2021 CHEMISTRY FORM 4
iron?
A. Chlorine, fluorine, nitrogen, oxygen, carbon
B. Fluorine, chlorine, oxygen, nitrogen, carbon
C. Carbon, nitrogen, oxygen, chlorine, fluorine
D. Nitrogen, oxygen, carbon, fluorine, chlorine
E. Fluorine, nitrogen, oxygen, chlorine, carbon
(iii) The metal nitrate which will NOT give a metal oxide on heating is
(iv) Which of the following pairs of compounds can be used in preparation of calcium sulphate?
(v) Three elements, X, Y and Z, are in the same period of the periodic table. The oxide of X is amphoteric, the oxide of Y is basic and the oxide of Z is acidic. Which of the following shows the elements arranged in order of increasing atomic number?
(viii) Two substances are allotropes of carbon if they:
A. both reduce heated iron (III) oxide to iron
B. have different crystalline structure
D. have equal masses
C. have equal shape
E. have the same arrangement of atoms
(ix) The gas formed when dilute nitric acid reacts with magnesium metal is;
2. Match the following items in list A with those in those in List Bbt writing the correct response beside the item number in answer booklet given.
LIST A | LIST B |
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|
SECTION B (70 marks)
3. (a) Differentiate a compound from an element
(b) State the rules used to assign symbols of elements
4.Desribe how you can test for sulphur dioxide gas
(b) What is the effect of presence of sulphur dioxide in the atmosphere?
5. (a) State three commercial uses of water
(b) Explain how we can establish that a given liquid is water.
6. Identify the substances by using the following information:
7. The preparation of ammonia in the laboratory is done by heating a mixture of ammonium chloride and sodium hydroxide.
(a) (i) Write a balanced chemical equation for the above reaction.
(ii) Using balanced chemical equations, state how ammonia reacts with hydrogen chloride gas and heated copper (II) oxide.
(b) (1) State two uses of ammonia.
(ii) Name the catalyst used in the preparation of ammonia.
(c) Explain each of the following reactions, giving observations and equations.
8. 6. Figure 1 below represents the laboratory preparation of hydrogen chloride gas.
(a) Name the parts labelled A, B, C and D.
(b) (i) Do you think the gas can be collected over water? Give reasons for your answer.
9.(a)What is fractional distillation?
(b) Give two applications of fractional distillation in the industry.
10.(a) Give four difference between the two carbon allotropes
(b) Give a reason why graphite is used as electrolyte
11. What is displacement reaction?
(b) What will happen when chlorine is bubbled through potassium iodide?
12. (a) Sodium, magnesium, zinc, copper and silver are five metals which appear in this order in the activity series; sodium being the most reactive and silver the least reactive. Which one of these metals is:
SECTION B.(15 MARKS)
Answer only one question.
12. The preparation of ammonia in the laboratory is done by heating a mixture of ammonium chloride and sodium hydroxide.
(a) (i) Write a balanced chemical equation for the above reaction.
(ii) Using balanced chemical equations, state how ammonia reacts with hydrogen chloride gas and heated copper (II) oxide.
(b) (1) State two uses of ammonia.
(ii) Name the catalyst used in the preparation of ammonia.
(c) Explain each of the following reactions, giving observations and equations.
13. Despite its corrosiveness, sulphuric acid is very important in the industry, Explain six industrial uses of sulphuric acid.
FORM FOUR CHEMISTRY EXAM SERIES 37
FORM FOUR CHEMISTRY EXAM SERIES 37
THE PRESIDENT'S OFFICE
MINISTRY OF REGIONAL GOVERNMENT AND LOCAL GOVERNMENT
PRE-NATIONAL EXAMINATION SERIES-1
CHEMISTRY FORM-4
2020
TIME: 3:00 HRS
Instructions
Atomic masses: H 1, O- 16, N- 14, S = 32, Zn - 65, Cl -35.5, cu - 64.
Avogadros number= 6.02 x 1023
GMV at s.t.p =22.4 dm3 .
1 Faraday= 96,500 coulombs.
Standard pressure = 760 mm Hg. Standard temperature 273 K.
1 litre =1 dm3 =1000 cm 3.
SECTION A (15 Marks)
Answer all questions in this section.
1. For each of the items (i) — (x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) "Water is referred to as the universal solvent". What does this mean?
(ii) A current of 0.2 A was passed through an electrolyte for 16 minutes and 40 seconds. What is the quantity of electricity produced in coulombs?
(iii) Substance X liberates chlorine gas from acidified potassium chloride. The behaviour of X is described as:
(iv) Which carbonate is the most stable to heat?
(v) Aluminium does not react with water and does not corrode much in air because
(vi) Which of the following compounds does NOT belong to the alkenes homologous series?
(vii) Which of the following is NOT among the composition of air?
(viii) Chlorine ion, Cl- differs from chlorine atom because it has
(ix) Which of the following pairs of compounds can be used in the preparation of calcium sulphate?
(x) Which of the following solutions is the most concentrated?
2. Match the items in List A which the responses in List B by writing the letter of the correct response beside the item number in the answer booklet provided.
LIST A | LIST B |
|
|
SECTION B (70 Marks)
Answer all questions in this section.
3. (a) (i) State Avogadro’s law of gaseous volume.
(ii) Find the volume of oxygen gas required to burn completely 1 dm3 of methane. CH4 + 2O 2(g) ? CO 2 + 2H 2O.
(iii) What is the volume of carbon dioxide formed in the reaction at (ii) (4 marks)
(b) Define the following terms:
(i) Mole
(ii) Molecular weight (2 marks)
4. (a) Ammonia gas can be prepared by heating an ammonium salt with an alkali
(i) Name the most common pair of reagents suitable for this reaction.
(ii) Write the equation for the reaction. (4 marks)
(b) Ammonia is very soluble in water and less dense than air. How does each of the properties determine the way in which ammonia is collected in a gas jar?
5. (a) Differentiate empirical formula from molecular formula
(b) Calculate the empirical formula for a compound with the following composition: lead 8.32 g, sulphur 1.28 g, oxygen 2.56 g (relative atomic wt of lead = 207, sulphur = 32, oxygen = 16)
6. (a) Classify the following reactions into oxidation and reduction reactions.
(i) S( s) + O 2( g) ? SO 2( g)
(ii) N2( g) + 3H 2( g) ? 2NH 3( g)
(iii) Fe2+ (aq) e ? Fe3+ (aq)
(iv) Fe3+ (aq) e ? Fe2+ (aq) (4 marks)
(b) What is the oxidation number of iron in iron (III) chloride? (3 marks)
7.(a) Explain the meaning of the following:
(i) Malleable
(ii) Ductile
(iii) Brittle
(b) Give an account of the following
(i) Anhydrous copper (II) sulphate becomes coloured when exposed to the air for a long time.
(ii) Carbon dioxide can be collected by the downward delivery method.
(iii) Concentrated sulphuric acid is not used for drying hydrogen sulphide gas.
(iv) Sodium metal is kept in paraffin oil.
8. (a) (i) What is the first step to take when you want to identify the contents of a given salt containing one anion and one cation?
(ii) In a solution of water, identify a solute and a solvent. Justify your answer.
(b) Sodium is a solid while chlorine is a gas at room temperature although they are in the same period in the periodic table. What is the cause of this difference?
9. (a) (i) Name three gases which should not be produced in order to prevent the destruction of ozone layer.
(ii) List and explain three effects of ozone layer depletion.
(b) Lack of safe water for domestic and industrial uses is a serious problem in most of Tanzanian towns. The major cause of this problem is pollution in the water sources. Slate three methods that could make water from a pond or a well be safe for drinking.
10. (a) (i) Name the products formed when nitrates of potassium and zinc decompose by heat.
(ii) Suggest why the nitrates of zinc and potassium behave differently on heating.
(b) Mention two uses of sodium nitrate.
11. (a) Which ways are the fossil fuels detrimental to the environment? Give four points.
(b) Briefly explain how biogas is produced by using domestic waste.
12. (a) (i) Define isomerism.
(ii) Draw and name two structural formulae of the isomers of C4H8.
(b) Carbon dioxide can be prepared by adding an acid to calcium carbonate.
(i) Using a named acid, write a balanced chemical equation for the reaction. (ii) Name all the products formed in (b) (i)
SECTION C (15 Marks)
Answer one (1) question from this section.
13. Describe the cause, two effects and measures to be undertaken in order to prevent/reduce the amounts of acid rain.
14. 0.48g of a metal, M was placed in a test tube and hot copper (II) sulphate solution was added to it and stirred until the reaction stopped. The metal (M) displaced copper from copper (II) sulphate solution. Copper was filtered, washed with water, dried at 1000 C and the mass found to be 1.27g. Given that, the balanced chemical reaction that occurred is M (s) + CuSO 4(aq) MSO 4(aq) + Cu (s)
(a) Calculate;
(b) State the appearance of the metal formed (Cu).
(c) With ionic equations, explain why the reaction can be considered to involve both oxidation and reduction.
FORM FOUR CHEMISTRY EXAM SERIES 34
FORM FOUR CHEMISTRY EXAM SERIES 34
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, LOCAL ADMINISTRATION AND LOCAL GOVERNMENT
CHEMISTRY- POST-MOCK- EXAMINATION-JUNE
FORM FOUR
Time 3:00 Hours JUNE 2020
INSTRUCTIONS.
Atomic masses: H 1, O- 16, N- 14, S = 32, Zn - 65, Cl -35.5, cu - 64.
Avogadros number= 6.02 x 1023
GMV at s.t.p =22.4 dm3 .
1 Faraday= 96,500 coulombs.
Standard pressure = 760 mm Hg. Standard temperature 273 K.
1 litre =1 dm3 =1000 cm 3.
SECTION A: 15 MARKS.
MULTIPLE CHOICE QUESTIONS.
1. For each of the items (i) — (x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) When methane undergoes substitutional reaction with excess chlorine, what is the final product?
(ii) The following are the uses of chromatography except:
(iii) Which of the following sets of processes uses a gas that ignites with a "pop" sound when a lighted splint is passed through it?
(v) A current of 0.2 A was passed through an electrolyte for 16 minutes and 40 seconds. What is the quantity of electricity produced in coulombs?
(v) Substance X liberates chlorine gas from acidified potassium chloride. The behaviour of X is described as:
(vi) Which of the following compounds does NOT belong to the alkenes homologous series?
(vii) When a burning fuel produces blue color it means there is
(viii) Which method could be used to separate the products in the following equation?
(ix) Which of the following is NOT among the composition of air?
(x) Which of the following pairs of compounds can be used in the preparation of calcium sulphate?
2. Match the descriptions in List A with the corresponding scientific procedures in List B by writing the letter of the correct response besides the item number in the answer booklet provided.
List A | List B |
|
|
3. (a) Copper obtained from copper pyrites (CuFeS2) is impure for electrical wiring and has to be purified by electrolysis.
(i) Name the electrolyte and the electrodes used during electrolysis.
(ii) Write the observations that can be made during the electrolysis.
(b) The following flow diagram shows the stages in the contact process
(i) Give the names of element A, catalyst B and an acid C.
(ii) Write a balanced chemical equation for the formation of sulphur trioxide in stage 2
4. (a) Suggest one method of separating each of the following:
(i) Green solution from leaves.
(ii) Alcohol from water.
(b) Elements K, L, M and N have atomic numbers 6, 8, 9 and 20 respectively. Classify each element into its respective period and group.
5. (a) Distinguish manures from fertilizers. Give an example in each case.
(b) The following equation shows the reaction between hydrogen and iodine gas to form hydrogen iodide gas,H2(g) + I2(g) ? 2HI (g) ?H= -800Kj/mol. Giving a reason, explain what would happen to the position of equilibrium if
(i) temperature is lowered.
(ii) hydrogen iodide gas is pumped into the system.
6. (a) State three main physical properties of water and show the usefulness of each property.
(b) State three industrial application of electrolysis.
7. (a)An atom M has an atomic number 14 and mass number 28.
(i)What is the number of protons and neutrons?
(ii) Write the electronic configuration of atom M.
(b) Calculate the volume of water which was produced when 1,120 cm3 of oxygen at s.t.p. was liberated during the decomposition of hydrogen peroxide. The density of water = 1.0 g/cm3
8. (a) Briefly explain why the mixture with equal boiling point cannot be separated by simple fractional distillation.
(b) The preparation of ammonia in the laboratory is done by heating any ammonium salt with an alkali.
(i) Write a balanced chemical equation for the preparation of ammonia gas.
(ii) State two uses of ammonia.
9. (a) Name two elements which are expected to show similar chemical reaction with magnesium. What is the basis for your choice?
(b) State the main raw material and the process involved in the manufacture of the following products.
10.(a) Give three advantages of using chemical equations over word equations.
(b) You are provided with a compound composed of 22.2% zinc, 11.6% sulphur, 22.3% oxygen, and the rest percentage is water of crystallization. Calculate the molecular formula of the compound if its molecular mass is 283. (7 marks)
11 . A Form Three student conducted experiments in the laboratory to synthesize nitrogen, ammonia and ethane. The experimental results were tabulated as follows:
Experiment | Reagents | Conditions | Products |
1 | Lead nitrate | Heat | Lead oxide, oxygen gas and nitrogen gas |
2 | Gaseous hydrogen and gaseous nitrogen | Catalyst | Ammonia gas |
3 | Ethene gas and hydrogen gas | Catalyst | Ethane |
Write word equations with corresponding chemical equations to summarize the reactions taking place in each of the experiments I to 3. (7 marks)
12.Assume that you are a chemist in a chemical plant that deals with the production of chlorine gas You want to produce 100 litres of chlorine gas per hour so that you can reach the company’s goal of producing 2400 litres every day. What current of electricity will you allow to flow per hour?
13. Describe five causes and effects of soil pollution.
14.Describe four common stages for the extraction of metals. Does the extraction of gold follow all four stages? Give reasons.
Get more of these from www.learninghubtz.co.tz
FORM FOUR CHEMISTRY EXAM SERIES 19
FORM FOUR CHEMISTRY EXAM SERIES 19
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, LOCAL ADMINISTRATION AND LOCAL GOVERNMENT
CHEMISTRY- MOCK- EXAMINATION-MAY
FORM FOUR
Time 3:00 Hours MAY 2020
INSTRUCTIONS.
1 Litre = 1dm3 = 1000cm3
G.M.V at STP = 22.4dm3
Avogadro’s constant = 6.02 x 10 23 particles.
SECTION A: 15 MARKS.
(i) Which among the given list of metals arranged in order of decreasing reactivity with steam from left to right is correct?
(ii) A study current of 4A was passed through an aqueous solution of Copper Sulphate for 1800seconds. Mass of Copper deposited will be:
(iii) Which of the following statement is true? Avogadro’s Constant is the number of?
(iv) An organic compound of structural formula …………………………… belongs to homologous series of:
(v) The atmosphere effect of burning fuel such as wood and petrol oils is to:
(vi) Elements loose or gains electrons to form.
(vii) Which of the following groups of organic compounds is prepared by dehydration of corresponding alcohol?
(viii) Which of the following is most ductile?
(ix) The same current passing through solution of the same concentration of silver nitrate and Copper Sulphate liberates 0.23g of Silver (equivalent weight = 108). The weight of Copper that will be liberated, (equivalent weight 31.8) is?
(x) In a blast furnace carbon monoxide is prepared by passing carbon dioxide over red – hot coke. Carbon dioxide is:
2. Match the items in List A with responses in List B by writing the letter of correct response beside the item number in List A.
LIST A | LIST B |
(i) Isomers (ii) Polymerization (iii) Ethanoic acid (iv) Lubricating oils (v) Homologous series
|
|
SECTION B:
3. (a) Give the reason for use of carbon dioxide
(i) As a fire extinguisher ( ½ marks)
(ii) As a refrigerant ( ½ marks)
(iii) In baking. ( ½ marks)
(b) Explain what will happen when carbon monoxide reacts with:
(i) Oxygen ( 1 marks)
(ii) Concentrated sodium hydroxide ( 1 marks)
(iii) Copper II Oxide. ( 1 marks)
(c) (i) Outline steps in preparation of charcoal ( 11/2 marks)
(ii) Mention two chemical properties of charcoal. (1 marks)
4. (a) Give two example for each or the following
(i) Strong acid ( 1 marks)
(ii) Strong alkali ( 1 marks)
(b) Identify the products formed when strong acid react with
(i) CuO(s) ( 11/2 marks)
(ii) NaOH(aq) ( 11/2 marks)
(c) Explain the meaning of the following and give two examples in each case.
(i) PH scale of an acid ( 1 marks)
(ii) Organic Acid. ( 1 marks)
5. (a) Describe the effect of:
(i) Strongly heating a piece of marble in Bunsen burner flame. ( 11/2 marks)
(ii) Moistening the residue (1) above with water. ( 11/2 marks)
(b)
(i) For what reason is slaked lime added to soil in gardening? ( 2 marks)
(ii) Why is concentrated sulphuric acid used as drying agent? ( 2 marks)
6. The preparation of ammonia M the laboratory is done by heating a mixture of ammonium chloride and sodium hydroxide.
(a)
(i) Write a balanced equation for the reaction ( 11/2 marks)
(ii) Use equations to show how ammonia reacts with hydrogen chloride gas and healed Copper II Oxide. ( 11/2 marks)
(b)
(i) State two uses of ammonia ( 1marks)
(ii) Name the catalyst used in preparation of ammonia ( 1marks)
(c) Explain each of the following reactions giving observation and equations.
(i) Aqueous ammonia is added to iron (III) Chloride, little by little until in excess. ( 1marks)
(ii) Sodium nitrate is strongly heated. ( 1 marks)
7.
a) Draw a well labeled diagram of non – luminous flame of Bunsen burner. 1 marks)
b) Explain the meaning of:
(i) Malleable ( 1/2 marks)
(ii) Ductile ( 1/2 marks)
(iii) Brittle ( 1 marks)
(c) Give an account for the following:
(i) Anhydrous Copper II Sulphate becomes coloured when exposed to air for long time.
( 1 marks)
(ii) Carbon dioxide can be collected by down ward delivery method. ( 1 marks)
(iii) Concentrated sulphuric acid is not used for drying hydrogen sulphide. ( 1 marks)
(iv) Sodium metal is kept in paraffin oil. ( 1 marks)
8.
a) Element A, B, C and D have atomic numbers 6, 8, 17 and 20 respectively. Write electronic structure of those elements ( 2 marks)
b) Write down the formulae of simplest compounds you would expect when;
(i) A and B combine chemically ( 1/2 marks)
(ii) C and D combine chemically ( 1/2 marks)
c)
(i) What types of bonding you would expect between compounds above? ( 1 marks)
(ii) List three differences between bonds you have identified above ( 3 marks)
9. (a)
(i) Name the product formed when nitrate of potassium and Zinc decompose by heating.
( 11/2 marks)
(ii) Suggest why the nitrate of Zinc and potassium behave differently when heating.
( 11/2 marks)
(b) Mention four uses of sodium nitrate. ( 4 marks)
10.
a) Giving four reasons, explain why people who use hard water can expect higher costs than people who use soft water. ( 3marks)
b) Suggest one method for separation of each of the following
(i) Iodine and sand ( 1marks)
(ii) Green solution form leaves ( 1marks)
(iii) Alcohol and water ( 1marks)
(iv) Iron fallings and powdered calcium carbonate. ( 1marks)
11. (a) A current of 0.5A were made to flow through silver voltmeter for 30 minutes. Calculate mass of silver deposited and equivalent weight of silver. ( 2marks)
(b) Explain the following reactions giving one example in each.
(i) Addition reaction ( 2marks)
(ii) Elimination reaction. ( 2marks)
12. (a) With an aid of chemical equations, explain the following terms,
(i) Esterification reaction ( 1marks)
(ii) Substitution reaction ( 1marks)
(iiii) Double decomposition reaction ( 1marks)
(b) Give a reason why alluminium is used in;
(i) Cooking Utensils ( 1marks)
(ii) Overhead Electricals ( 1marks)
(iii) Window Frames ( 1marks)
SECTION C:
Answer Only one Question.
12. Describe the two causes, two effects and measures to be undertaken in order to prevent/reduce the amount of acidic rain. (15 marks)
13. Consider the following.
Use Le Chaletires Principle to describe how the rate of production of D can be altered. (15 marks)
FORM FOUR CHEMISTRY EXAM SERIES 12
FORM FOUR CHEMISTRY EXAM SERIES 12
THE PRESIDENT’S OFFICE
THE MINISTRY OF EDUCATION AND VOCATIONAL TRAINING
MID TERM EXAMINATIONS-MARCH 2020
032 CHEMISTRY- FORM FOUR
Duration: 2:30 Hours
INSTRUCTIONS:-
1.This paper consists of sections A,B and C
2.Answer all questions in all sections
3.Whenever necessary, the following constructs may be used.
Atomic masses: C=12 O=16, H=1, Mg = 24, Na=23, Cl= 35.5, Ca= 40, Cu= 63.5.
Avogadro’s constant = 6.02 x 1023 particles
Molar volume of gas at S.T.P = 22.4dm3mol -1 or 22400cm3 mol -1
SECTION A (15MARKS)
The graph shows the results.
Mass of beaker
And contents
| |
| |
Time
The two solutions could be:-
The diagram below show the test- tubes containing the experiments. Which metal is placed in each test – tube?
| Test tube 1 | Test tube 2 | Test tube 3 |
A | Iron | Silver | Magnesium |
B | Iron | Magnesium | Silver |
C | Magnesium | Silver | Iron |
D | Silver | Iron | Magnesium |
The question for the reactions is
2H2O2 Mno2 2H2O+O2
(aq) (l) (g)
LIST A | LIST B |
|
|
SECTION B:70 MARKS
Answer ALL questions
(10 marks)
-Calculate;
i)The molar concentration of the acid
ii)The value of x
d) Write down balanced chemical equation for the reaction involved. (C=12,H=1,0=16)
(10 marks)
| |
| |
14
pH
12 A
10
8
6 B
4
2
0 Volume of hydrochloric acid added(cm3)
(10marks)
1A |
|
| |||||||
3B | 4 | 5 | 6 | 7 | 8C | 9 | 10E | ||
11M |