THE OFFICE OF THE PRESIDENT, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT.

SECONDARY EXAMINATION SERIES

MARCH 2025

CHEMISTRY FORM THREE

TIME: 2:30HRS

INSTRUCTIONS

1.    This paper consists of three section A, B and C with a total of eleven (11) questions.
2.    Answer all questions from section A and B and two questions from section C.
3.    Section A carries sixteen (16) marks, section B carries fifty four (54) marks and section C carries thirty (30) marks.
4.    All writing should be in blue ink except diagrams which must be in pencil.
5.    All communication devices and any unauthorized material are not allowed in the examination room.
6.    Write your Examination number at the top right corner of every page.

SECTION A (16 Marks)

(Answer all questions in this section)

1. For each of the items (i –x) choose the most from the given alternatives and write its letter beside the item number in the answer sheet (booklet) provided.

i. Which of the following is not a use of a solvent? 

1.  Bleaching agent
2.  Greasing.
3.  Stain removal.
4.  Cleaning
5.   Universal solvent

ii. In which step of scientific procedures does the hypothesis is either proved or disproved?

1.  Data collection and analysis.
2.  Experimentation.
3.  Data interpretation
4.  Formulation of hypothesis.
5.   Conclusion

iii. Which of the following groups consist of home Care products?

1.  Yeast, plastic and disinfectant.
2.  Clothes, soap and stone.
3.  Air freshener, detergent and antiseptic.
4.  Petrol, air freshener and paints.
5.   Air freshener, detergent and disinfectant

iv. An electric current of 0.2A was passed through an electrolyte for 16.67minutes. The quantity of electricity passed is;

1.  200.04cuolombs
2.  2000.004cuolombs
3.  1000cuolombs
4.  0.254cuolombs
5.   0.00789culombs

v. What is the correct meaning of ionization energy?

1.  Energy required to remove an electron from the inner most shell
2.  Energy required to remove electron from the outer most shell
3.  Energy required to add electron to the inner most shell
4.  Energy required to add electron to the outer most shell
5.   Energy required to attract electron towards the nucleus of an atom

vi. An increase in temperature of a gas in enclosed system/container causes an increase in pressure of the gas. This is because it increase the.

1.  Number of gas molecules
2.  Combination of gas molecules
3.  Number of collision between gas molecules
4.  Average velocity of a gas molecules
5.   Kinetic energy of the gas particles

vii. Which of the following is not the use of chromatography?

1.  To analyze blood in crime scenes
2.  To detect different fibres
3.  To detect water pollution
4.  To bleach dye or colour
5.   To test purify of organic substance

viii. Which of the following pairs constitute the best methods for treating and purifying water?

1.  Chlorination and aeration 
2.  Chlorination and decantation 
3.  Chlorination and filtration
4.  Chlorination and sedimentation
5.   Chlorination and distillation

ix. 1.4g of potassium hydroxide is dissolved in water to form 250cm³ of Solution.

What is the Molarity of this solution?

1.  0.001M
2.  0.1M
3.  1.4M
4.  5.6M
5.   6.0M

x. An electric current was passed through a concentrated solution of hydrochloric acid using carbon electrodes. The substance liberated at anode was.

1.  Copper
2.  Hydrogen
3.  Oxygen
4.  Sodium
5.   Chlorine

2. Match the items in LIST A with the responses in LIST B by writing the letter of the correct response besides the item number in the answer sheet provided

3. Aisha drew a periodic table and then put a shadow on the element with atomic number 8 

(a) What type of chemical bond is found between atoms of the element?

(b) Compound X contains 24.24% Carbon, 4.04% Hydrogen and 71.72% Chlorine.

Given that, the vapour density of X is 49.5.

(i) Calculate molecular formula of the compound X

4. (a) Write ionic equation for the precipitation of Barium sulphate from Barium chloride and Sodium sulphate

(b) It is not advisable to sleep inside the house which is not well ventilated with a burning wooden charcoal. Give a reason for that and write the chemical equation to support your answer.

(c) Consider the following elements of group seven n order of which they appear in their group in the periodic table F, C 1, Br, and I

1.          Which element is more electronegative
2.          Name the least electronegative element
3.          Which element has the largest atom?
4.          Write the electronic configuration of the chlorine atom (9marks)

5. (a) Distinguish between Temporary Hardness and Permanent Hardness of Water basing on their ions.

(b) By use of equations, show how each of the type of hardness in (a) above can be eliminated.

(c). Giving four reasons, explain why people who use hard water can expect high costs than people who use soft water. (9 marks)

6. (a)Catherine is planning to make fire for cooking ugali for her family. What are necessary conditions which must be present so that she can make fire successfully for cooking ugali for her family?

(b)Give for each of the followings

1. Water is universal solvent
2. Some metal like zinc do not get rust.
3. Chlorine gas is collected by downward delivery
4. Carbon dioxide turns lime water into milky colour.

7. (a)What do you understand the term chemical equation?

(b)Write ionic equation for the following chemical reactions.

1.    Milk of magnesia is used to relieve indigestion
2.    A divalent metal displacing monovalent metal from its soluble nitrate

8. (a) Differentiate the temporary hardness of water from permanent hardness of water basing on their content.

(b) Consider the sample of water taken indifferent places at Arusha region. The samples were boiled and treated with the soap while others were treated with soap before boiling to obtain different results:

(i) Which sample contains temporary hardness of water? (Give reason)

(ii) Which sample contains permanent hardness of water? (Give reason)

(iii)   What do you think will be the cause of variation of volume of soap of Maroroni water? 

(c) Mention the methods (s) used to soften sample of water at Njiro.

9. 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

10. 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

10. (a) Gas A was prepared in the laboratory by isolating it from atmospheric air. During it's preparation air was allowed to pass through sodium hydroxide then over heated copper metal.

(i) Identify gas A.

(ii) By using equation, explain what happened when gas A passed through sodium hydroxide and in heated copper metal.

(iii) Write two uses of gas A

(b) (i) What will happen when copper is strongly heated in air at higher temperature and lower temperature respectively.

(ii) Explain how the pure copper is obtained from its ore?

SECTION C. 15 MARKS

11. (a) Makame’s daughter was sick. When he took her to the hospital, she was

Prescribed some medicine including a bottle of syrup. The bottle was written “shake well before use”.

(i) What does this statement signify?

(ii) Give two differences between the prescribed medicine in 10(a) above and the mixture of sugar and water.

(b) Students of mining course at a certain college conducted research on extraction of iron. They found that iron can be obtained from its ore in four stages. Briefly explain to them the four stages they should follow to extract it.

PRESENT’S OFFICE, REGIONAL ADMINISTRATION

AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES

CHEMISTRY FORM THREE

MID-TERM EXAMS – AUG/SEPT – 2024

TIME: 2:30 HRS

INSTRUCTIONS 

SECTION A 

Answer all questions in this section

i. Which of the following groups consist of home Care products?

1. Yeast, plastic and disinfectant.
2. Clothes, soap and stone.
3. Air freshener, detergent and antiseptic.
4. Petrol, air freshener and paints.
5. Air freshener, detergent and disinfectant

ii. An electric current of 0.2A was passed through an electrolyte for 16.67minutes. The quantity of electricity passed is;

1. 200.04cuolombs
2. 2000.004cuolombs
3. 1000cuolombs
4. 0.254cuolombs
5. 0.00789culombs

iii. The copper (II) oxide reacts with hydrogen gas to form copper metal and water. What will be the mass of reduced element?

1. 4g.
2. 64g.
3. 18g.
4. 80g.
5. 40g

iv. During the steam reforming method in industrial preparation of hydrogen, the steam reacts with what compound to produce hydrogen gas?

1. Water.
2. Carbon monoxide.
3. Methane.
4. Sulphur dioxide.
5. Oxide

v. Domestic utensil made up of iron rust easily as a result of the presence of:-

1. Air and fire
2. Air and water 
3. Water and Oil 
4. Air and Oil 
5. Water and oil.

vi. What is the correct meaning of ionization energy?

1. Energy required to remove an electron from the inner most shell
2. Energy required to remove electron from the outer most shell
3. Energy required to add electron to the inner most shell
4. Energy required to add electron to the outer most shell
5. Energy required to attract electron towards the nucleus of an atom

vii. Which of the following pairs constitute the best methods for treating and purifying water?

1. Chlorination and aeration 
2. Chlorination and decantation 
3. Chlorination and filtration
4. Chlorination and sedimentation
5. Chlorination and distillation

viii. An electric current was passed through a concentrated solution of hydrochloric acid using carbon electrodes. The substance liberated at anode was.

1.  Copper
2.  Hydrogen
3.  Oxygen
4.  Sodium
5.  Chlorine

ix. If element Q of group (H) combines with element R of group (IV) what will be the formula of the resulting compound.

1.     R2Q
2.     QR₆
3.     R₃Q
4.    R3Q
5.      Q2R

x. The process of giving away water of crystallization to the atmosphere by a chemical substance is called.

1.     Efflorescence
2.     Deliquescence
3.     Hygroscope
4.    Sublimation
5.      E.Vaporization

2. Match the items in List A with responses in List B by writing the letter of the correct response beside the items number in the answer booklet provided.

SECTION B

Answer all questions in this section

3. You are provided with the following fuels fire woods, natural gas, charcoal and kerosene.

1. Giving three reasons, explain why natural gas is the best option among the fuels given above for domestic purpose.
2. Giving four reasons, explain why fire wood and charcoal which are cheap and most available fuels are not recommended for domestic uses.

4. (a) Students are advised to use a non- luminous flame for heating in the laboratory

(i) Explain how a Bunsen burner produces a non- luminous flame

(ii) Give a reason as to why advice above given to students.

(iii) What are the functions of the air holes and barrel in the Bunsen burner?

(b)Why hydrogen peroxide preferred to potassium chlorate during preparation of oxygen gas?

(c) Why iron is not usually recommended in construction of steam pipes and boilers?

(d) What would happen to a well stoppered bottle full of water left in deep freezer over night? Why does this happen.

5. (a) Neutralization is applied in various useful situations with the aid of balanced chemical equation where necessary; describe any four usefulness of neutralization.

(b) 2.91 g of a monobasic acid, HX, were dissolved in water and made up to 250 cm³ with water. This solution was titrated with 0.108 M sodium hydroxide solution. 25 cm³ of the sodium hydroxide solution required 22.5 cm³ of the HX solution for complete neutralization. The equation for the reaction is.

HX _(aq) + NaOH_(aq) → NaX_(aq) + H₂O_(l)

(a) Calculate the concentration in (i) g l^-1 (ii) mol l^-1 of the acid.

(b) Calculate the molar mass of HX.

6. (a) Janeth heated compound “W” in a test tube and observed that a brown gas was produced, residue X formed. Also when she inserted a glowing splint into the test tube rekindled.

1. Which gas rekindled the glowing wooden splint in the test tube.
2. Identify compound “W” and residue “X”
3. Write down a chemical equation for the reaction that took place.

2. Explain the observations that would be made when aqueous ammonia is added drop by drop until in excess on a solution W

7. (a)Sodium chloride (NaCI) and hydrogen Chloride (HCI) are both chloride Compounds.Differentiate the two compounds by giving three reasons. 

(b)(i)Differentiate empirical formula from molecular formula. cetain compound formed by Sulphur and Oxygen contains 40.1% sulphur by mass.Workout the empirical formula of this compound.

8. (a) 25cm³ of 0.1MHCl were neutralized by 23cm³ of Na₂CO₃ solution. Calculate the concentration of the alkali in grams per litre.

(b)Suggest a suitable indicator of each of the following titrations

1. Hydrochloric acid against ammonia solution
2. Sulphuric acid against sodium hydroxide solution
3. Ethanedioic acid against potassium hydroxide solution

9. (a)What do you understand the term chemical equation?

(b)Write ionic equation for the following chemical reactions.

1. Milk of magnesia is used to relieve indigestion
2. A divalent metal displacing monovalent metal from its soluble nitrate

10. (a)Explain the meaning of each of the following terms.

1. Reversible reaction.
2. Dynamic equilibrium

(b)The industrial oxidation of Sulphur dioxide is summarized in the equation below.

2SO_3(g) + O_2(g)  2SO_3(g) H=-94.9 Kjmol^-1

What will be the effect of each of the following on the production of Sulphur trioxide?

1. Increase in moles of Sulphur dioxide
2. Increase in pressure
3. Decrease of temperature
4. Decrease of moles of Sulphur dioxide.

(c)Briefly explain how each of the following factors affects the rate of a chemical reaction.

1. Temperature
2. Pressure
3. Concentration
4. Catalyst
5. Surface area

(d)Give one good reason for the following

1. Fruits ripe faster during summer than during winter
2. Steel wire get rust faster than iron nails.

SECTION C

11.

1.      Explain stages of extraction of mild reactive metals
2.     Why is the extraction of Iron a reduction process
3.      Explain with equations extraction of iron in the blast furnace
4.     What are environmental effects of metal extraction

PRESIDENT’S OFFICE, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES,

MID TERM ONE – MARCH-2024

CHEMISTRY FORM THREE

Time: 3Hours

Instructions 

1.         This paper consists of sections A, B, and C with a total eleven (11) questions.
2.         Answer all question in the sections A, B and two (2) questions from section C.
3.         Section A carries sixteen (16) marks, section B fifty four (54) marks and section C carries thirty (30) marks.
4.         All writing should be in blue or black pen, except for diagrams that must be drawn in pencil.
5.         Communication devices and any unauthorized materials are not allowed in the examination room.
6.         Write your Examination Number on every page of your answer booklet (s

SECTION A:  (16 MARKS)

Answer all questions in this section.

1.         For each of the following items (i-x) choose the correct answer from the given alternatives and write letter besides item number in the answer booklet provided.

1.     Which of the following is not a use of solvent

1. Bleaching agent
2. Greasing
3. Stain removal
4. Cleaning
5. Universal solvent

2.  In which step is scientific procedure does the hypothesis either proved or disapproved?

1. Data collection and analysis
2. Experimentation
3. Data interpretation
4. Formulation of hypothesis
5. conclusion

3.                         During the steam reforming method in industrial preparation of hydrogen. The steam reacts with what compound to produce Hydrogen gas

1. water
2. carbon monoxide
3. methane
4. sulphur dioxide
5. oxide

4.                         what will be simplest taste of hardness of water

1. shaking water with chalk
2. mixing water with soap detergent
3. formation of scum
4. shaking water with soap solution
5. formation of dolomite`

5.   Which of the following set of process uses a gas that ignites with a pop –sound when a lighted splint is passed through?

1. Balloon filling, welding, diving
2. Hardening of oil, balloon filling , welding
3. Hardening of oil, balloon filling and divings
4. Fuelling rocket, diving and welding
5. Balloon filling, fuel rocket and diving

6.                         The cause of permanent hardness of water is

1. CaCOh)₂
2. CaCHCO₃)₂
3. Mg (HCO₃)₂
4. Na₂SO₄
5. CaSO₄ 

7.    Domestic Utensils made of iron must rust easily on a result of presence of

1. Air and fire
2. Air and water
3. Water and oil
4. Water and oil
5. Water and oil

8.  Which of the following pairs constitutes the method of treating and purifying water

1. Chlorination and Aeration
2. Chlorination and Decantation
3. Chlorination and Filtration
4. Chlorination and Distillation
5. Chlorination and sedimentation

9.                         The process of giving away water of Crystallization to the atmosphere by a chemical substance is called

1. Efflorescence
2. Deliquesce
3. Hydroscope
4. sublimation
5. evaporation

10.   when water is added to an acid, that acid becomes

1. more acidic and its PH goes down
2. more acidic and its PH goes up
3. less acidic and its PH went down
4. less acidic and its PH went up
5. neutral and its PH become 7

2.         Match the properties of element in list A with the respective element in list B by writing the letter of correct response besides the item number in answer sheet provided

SECTION B

54 MARKS

Answer all questions.

3.         a) The modern periodic law is based on modification of the Mendeleev Periodic Law. Explain how the two theories differ from each other

b) Comment on the following statement

1.     lithium has large size than beryllium
2.  sodium is smaller than potassium
3.                         Give any four ions whose electronic configuration resemble to that of Neon.

4.         A) Magnesium burns in a carbon dioxide giving white solid and black solid sparks. The white solid dissolves in nitric acid leaving colorless solution R

1.     Write balanced equation for reaction that give white solid
2.  Identify solution R

B) Differentiate between suspension and solution

5.         a) The table below shows two brands of bottled water for drinking and concentration of different mineral ions in each brand. Study the table and answer question that follows

1.     Which brand of water is harder? Explain
2.  State the benefit of having calcium ions in water
3.                         Tap water is always treated before being used, state what is added to perform that function

b) Hydrogen and phosphorus are non metallic elements 

1.     Which one between the two is more electropositive
2.  Show your wake clearly write chemical formula and name of compound fotmed when two atoms combined

6.         A)State the main raw materials and process involved in manufacture of the following products

1.     Wood charcoal
2.  Coke
3.                         Lamp black
4.                         Animal charcoal

                b) Define the terms below

1.     Mole
2.  Molar mass

7.         A) Students are advised to use non-luminous flames for heating in laboratory.

1.     Explain how a Bunsen burner produces non- luminous flames
2.  Give a reason as to why the above flame is best
3.                         Give function of air holes in a barrel of Bunsen burner.

b) Explain why hydrogen is proffered to potassium chloride during preparation of oxygen gas.

8.         A) different salt behave differently when heated use a balanced chemical equation to show how Carbonate and Sulphate behave when subjected to heat

b) Write a balanced and ionic equation for reaction between sodium carbonate and hydrochloric acid 

c) Differentiate ionic equation from molecular equation

SECTION C

30MARKS 

9.         Aisha drew a periodic table and then put a shadow on element with atomic number 8

1.             What type of chemical bond is found between atoms of the element
2.             Compound X contains 24.24%, 4.04% hydrogen and 71.72%chlorine. Given that the vapor density of X is 49.5. calculate molecular formula of compound X
3.             If 0.5 g of hydrogen gas is exposed in air, what mass of water will be formed

10.    A) give two ways you can use to tell water os polluted

b) We have coal in Kuwira Mbeya region; the government authorities have allowed the use of coal for domestic and industrial purposes. What warning can you raise concerning the likely effects? Give five points

11.    Consider the diagram below

1.     Give the aim of the above process
2.  Identify the process of A to F
3.                         Give two importance of above diagram in our daily life

b) State weather the following is permanent change or temporary change 

1.     Dissolution of salt in water
2.  Rotting of mangoes

PRESIDENT OFFICE REGIONAL ADMNISTRATIONAND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES

COMPETENCE BASED ASSEMENT

032/1CHEMISTRY FORM THREE

ANNUAL EXAMINATIONS – 2023

Time: 3 Hours

Instructions

1. This paper consists of section A, B and C with a total of thirteen (13) questions.
2. Answer all questions in this paper
3. Calculators, cellular phones and any unauthorized materials are not allowed in the examination room
4. Write your Examination Numberon every page of your answer booklet(s)
5. The following constants may be used

Atomic masses:

H=1,C=12,O=16,N=14,Ag=108

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 = 1dm³= 1000cm³

SECTION A. (16 MARKS)

1. For each of the items (i) – (x), Choose the correct the answer from among alternatives given and write its letter in the answer sheet provided

1. Loose or floppy clothing is not allowed in the laboratory because;

1. Movement has to be fast
2. It will get wet when water splashes
3. It may catch fire or cause one to fall
4. It cause poor ventilation in the body
5. It prevents experiment from being conducted well

2. What mass of Suphuric acid (H₂SO₄) is found in 400cm³ of its 0.1M?

1. 2.67g
2. 9.8g
3. 4.89g
4. 3.92g
5. 8.69g

3. One of the Isotopes of an element X has atomic number Z and a mass number A. What is the number of Neutron contained in Nucleus of the element?

1. Z – A
2. A
3. A + Z
4. Z
5. A – Z

4. A solution of PH 5 is said to be

1. Strong base
2. Neutral
3. A weak acid
4. A strong acid
5. A weak base

5. In an experiment, 1930 coulombs Liberated 0.64g of copper when the same quantity of electricity. Was passed through a solution of silver Nitrate. What amount of silver was deposited?

1. 32g
2. 2.16g
3. 10.8g
4. 108g
5. 21.6g

6. In blast furnace carbon monoxide in prepared by passing carbon dioxide over a red hot coke. What is the chemical role of carbon dioxide

1. An accelerator
2. An oxidizing agent
3. A catalyst
4. A reducing agent
5. Flammable

7. The following shows four uses of iron, in which of these uses are the iron most likely to rust?

1. Iron bucket electroplated with zinc
2. Iron wired Alluminium electric cable

3. Iron hinges on gate
4. Alloyed piston
5. Panted iron gate

8. Alluminium does not react with water and does not corrode much in air. Why?

1. It is below hydrogen in reactivity series
2. It forms a stable carbonate which prevent reactions
3. The metal in coated with a protective coating of Oxide

4. It is very unstable
5. Does not react with water

9. When bumming fuel produce blue colour, it means there is

1. Adequate supply of Oxygen without production of soot
2. Inadequate supply of Oxygen without production of soot
3. Inadequate supply of Oxygen with production of soot
4. Adequate supply of Oxygen with production of more heat
5. Inadequate supply of Oxygen with production of more heat

10. The reason why white anhydrous copper II sulphate tums blue when exposed in atmosphere is that it.

1. Absorb moisture
2. React with Oxygen
3. React with carbon dioxide
4. Becomes dry
5. Release water to atmosphere.

2. Match items in LIST A with correct response in LIST B by writing the letter of correct response beside the item number in answer sheet provided.

SECTION B. (54 Marks)

Attempt all questions in this section

3. (a)Explain how the following differ from one another

1. A base and Alkali
2. An atom and isotope

(b) An organic compound P consists of 52.2% carbon 13% hydrogen and 34.8% Oxygen. The vapour density of P is 23. Calculate molecular formula of the compound.

(c) Calculate Oxidation number of Nitrogen in potassium nitrate.

4. (a)Give three applications of separation of mixture in our daily life.

(b) 20.0cm³of sodium hydroxide containing 8.0gdm³was required for complete neutralization of 0.18g of dibasic acid. Calculate the relative molecular mass of the acid

5. (a)State faraday’s Laws of electrolysis

(b) Dilute Silver Nitrate solution was decomposed by passage of electric current through it. What mass of Silver and what volume of Oxygen (measured at (STP) would be liberated in electrolysis by 9650C of electricity?

6. 5.3g of X₂CO₃ was dissolved in water to make 0.5 litre of a solution 25cm³ of this solution required 50cm³ of 0.1M HCl for complete reaction.

1. Write a balanced chemical reaction for complete neutralization
2. Calculate concentration of X₂CO₃ in moles dm^-3
3. What is the relative molecular mass of X₂CO₃
4. Give the name of element X

7. (a)What do you understand by the following terms

1. Mole concept
2. Molar volume of gas

(b)Consider the equation below for dissociation of Suphuric acid

H₂SO_4(aq)→ 2H_(aq)⁺+ SO₄^2-_(aq)

From equation, how many ions are there in 9.8g of sulphuric acid?

8. (a)Consider the following elements

¹⁶O₈,¹⁹F₉,²⁰Ne₁₀²³Na₁₁²⁴Mg₁₂. Atoms and ions of these elements can be 150-electronic (have same number of electrons)

1. Write down their symbols when they are ISO-electrode
2. Write down their common electronic arrangement in their ions and atoms

(b)Although Sulphur dioxide is an Oxide, It can be further Oxidized

1. Write an equation and Condition for further Oxidation of sulphur dioxide
2. Write down an equation showing how the product can be used industrially to obtain desired Materials to be produced.
3. Give the name for this industrial process
4. Write two uses of product formed by industrial process named in (iii) above

SECTION C (30 Marks)

Answerany twoquestions from this section

9. (a)Describe the extraction of sodium from its ore and Write all the reaction equation

(b) State four uses of sodium metal

10. (a) Preventing rusting, you should prevent contamination of water and air with iron and steel, also to avoid using material made from iron or steel. State the method that can be used to prevent rusting on each of the following

1. Iron sheet
2. Bridge and pipes
3. Ship
4. Machine parts

(b) Fire extinguisher is used to stop fire. List five types of fire extinguishers

11. (a)Briefly explain the following observation about a sample of hard water

1. When boils it forms white precipitate
2. After boiling, water forms a scum
3. Sodium carbonate makes the water completely soft

(b) With the acid of chemical equation, briefly describe the following processes

1. The removal of temporary hardness of water by boiling
2. The removal of permanent hardness of water by chemical means

PRESIDENT OFFICE REGIONAL ADMNISTRATION

AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES 

COMPETENCE BASED ASSEMENT

CHEMISTRY FORM THREE 

TERMINAL EXAMS MAY – 2023 

032/1

Time: 3 Hours 

Instructions

1. This paper consists of section A, B and C with a total of thirteen (13) questions.
2. Answer all questions in this paper
3. Calculators, cellular phones and any unauthorized materials 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

Atomic masses: 

H=1,  C=12,  O=16,  N=14,  Pb=108

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 = 1dm³ = 1000cm³

SECTION A

1. Choose the correct answer from the alternatives given below

(i) The best chemical warning signs that should be put on bottles containing kerosene is ……….

1. Corrosive
2. Toxic
3. Flammable
4. Explosive
5. Harmful

(vii) What volume of hydrogen gas will be produced when 1.3g of zinc granules react completely with excess dilute sulphuric acid at s.t.p?

1. 223cm³
2. 130cm³
3. 220cm³
4. 440cm³
5. 448cm³

(x) The following reaction 4NH_3(g) + 5O_2(g) → 4NO_(g) + 6H₂O (l) is an example of a

1. Redox reaction
2. Combination reaction
3. Esterification
4. Neutralization reaction
5. Decomposition reaction.

(iv) 10cm³ of 0.4M Sodium Hydroxide are added to 40cm³of 0.2M hydrochloric acid. The resulting mixture will be

1. Neutral 
2. Alkaline 
3. Dilute
4.  Acidic
5. Amphoteric

(viii) A metal nitrate which will not give a metal oxide on heating is:

1. Calcium nitrate 
2. Silver nitrate 
3. Lead nitrate
4. Copper nitrate
5. Zinc nitrate

(ix) When nitrogen gas is formed covalently how many electrons are shared between nitrogen atoms.

1. 2
2. 3
3. 6
4. 5
5. 4

9. Which of the following substances represent a group of acid oxides?

1. Carbon dioxide, carbon monoxide and Sulphur dioxide.
2. Sulphur trioxide, Nitrogen dioxide and Nitrogen monoxide
3. Carbon dioxide, Sulphur dioxide and dinitrogen oxide
4. Sulphur trioxide, carbon dioxide and Nitrogen dioxide
5. Carbon monoxide, nitrogen oxide and sulphur dioxide.

7. The reason why white anhydrous copper (II) Sulphate turns blue when exposed in Atmosphere is that it

1. Absorbs water vapour
2. Reacts with oxygen
3. Reacts with carbon dioxide
4. Become dry
5. Release water to the Atmosphere

10. Which action should be taken immediately after concentrated sulphuric acid is spilled on the skin?

1. It should be rinsed off with large quantities of running water.
2. It should be neutralized with concentrated NaOH
3. The affected area should be wrapped tightly and shown to a medical health provider
4. It should be Neutralize with solid CaCO₃
5. It should be neutralized with concentrated KOH

(x) The following is an example of organic acid

1. Hydrochloric acid
2. Phosphoric acid citric acid
3. Citric acid
4. Nitric acid
5. Carbonic acid

2.  Match the item in LIST” A” with the correct response in LIST” B”

SECTION B. (70 MARKS)

ANSWER ALL QUESTIONS FROM THIS SECTION

3. (a) If 0.5g of hydrogen gas are exploded in air, What is the mass of water formed?

(b) 2FeCl_3(aq) + H₂S(g) → 2FeCl_2(aq) + 2HCl + S_(s)

From above equation, calculate the mass of iron (II) Chloride formed by the excess of hydrogen sulphide gas on a solution containing 54.0g of iron (III) chloride.

4. (a)Find the molarity of a sample of sulphuric acid containing 98% by weight H₂SO₄ and having a density of 1.63gcm^-3_.

(b)Find the concentration in molarity of 2.70g of Sodium carbonate dissolved in 250cm³

5. 70.0cm³ of X₂CO₃ solution required 50.0cm³ of 0.2M HCI for complete neutralization.

1. Write the balanced chemical equation of the reaction.
2. Calculate the concentration of X₂CO₃ in

1. Molarity
2. g/dm³

3. If compound X₂CO₃ has molar mass equal to 106g, calculate the relative atomic mass of X.
4. What is the name and symbol of elements X.
5. Identify the period and group of element X.

6. An electric current was passed in series through solutions of calcium chloride and copper (II) sulphate. Carbon electrodes were used in both electrolytes.

If 1.5 litres of chlorine measured at S.T.P were produced, what volume of oxygen would also be produced? What mass of copper was produced?

7. Describe the industrial application of electrolysis.

8. State whether the reaction:

will proceed forward or backward under these conditions:

1. Pressure is increased,
2. Temperature is lowered,
3. More ammonia gas is removed,
4. Hydrogen gas is reduced if other factors are maintained.

9. (a)What is the source of the following in Haber process:

1. Hydrogen
2. Nitrogen

(b)What is the role of Silica gel in Haber process?

(c)Vanadium pentoxide is generally used as a catalyst in the contact process

Comment

(d) A catalyst can shift the position of a chemical equilibrium. Comment.

10. The alternative energy sources for the future could be biogas, geothermal, nuclear, wave, tide, wind and hydroelectric comment.

SECTION C. 15 MARKS

ANSWER QUESTION 11.

1. Enumerate four chief ores of iron.
2. How is iron extracted from its ore?
3. What is the role of the limestone in the extraction of iron?

PRESIDENT OFFICE REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES 

COMPETENCE BASED ASSESSMENT

032/1 CHEMISTRY FORM THREE 

NEW NECTA FORMAT-2023

MID-TERM EXAMS MARCH – 2023 

Time: 3:00 Hours 

Instructions

1. This paper consists of section A, B and C with a total of thirteen (13) questions.
2. Answer all questions in this paper
3. Calculators, cellular phones and any unauthorized materials 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

• Atomic masses: H=1, C=12, O=16, N=14, Pb=108
• 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 = 1dm³ = 1000cm³

SECTION A (16 Marks)

1. For each of items (i) – (x), Choose the correct answer from among the given alternative beside item number in answer booklet provided

1. The technician prefer to use blue flame in welding because

1. It is bright and non-sooty
2. It is light and Non-sooty
3. It is very hot and large
4. It is very hot and non-sooty

2. One of the following is not correct about coke being a better fuel than coal as it is

1. Does not produce carbon dioxide
2. Does not produce poisonous gas
3. Has higher heat content
4. It is clean and smokeless

3. An important property of Oxygen that differentiate it from other gases is

1. Bum and support combustion
2. Burn but does not Support combustion
3. Neither bums nor Support Combustion
4. Supports combustion but does not bum

4. Hard water which can be softened by boiling method contains dissolved

1. Calcium carbonate
2. Calcium sulphate
3. Magnesium Chloride
4. Magnesium hydrogen carbonate

5. The source of energy which when used can be made to be put into use again is known as

1. Fuel
2. Non-renewable energy
3. Renewable energy
4. Solar energy

6. One Isotope of an element has atomic number A and a mass number M. how many neutrons are contained in nucleus of atom?

1. M
2. A
3. A-M
4. M-A

7. The arrangement of electrons in the atomic number 15 may be represented as follows

1. 2:5:8
2. 2:8:5
3. 2:5:2
4. 8:2:5

8. Which of these methods can remove both temporary and permanent Gardness of water?

1. Using ion exchange chamber
2. Boiling
3. Using Calcium hydroxide
4. Evaporation

9. A weak acid is best described on

1. An acid that does not ionize completely
2. A dilute Acid
3. An acid that is harmless
4. An acid

10. Which is not an advantage of biogas

1. It is cheaper source of Energy
2. Pollutes the environment
3. It is renewable source of energy
4. Creates employment to the youth

2. (a)Match the terms in List A with explanation on List B and write the answer on spaces provided.

SECTION B (54 Marks)

Answer all questions in this section

3.

1. How can the society minimize the section encountered in use of charcoal and fire wood?
2. Briefly explain the concept of scientific procedure
3. What is the importance of scientific procedure in daily life?

4. (a)Give the meaning of the following

1. Basicity of an acid
2. The pH scale

(b)Categorize the following salts

1. PbSO₄
2. MgHSO₄
3. Zn(OH)Cl
4. MgHCO₃
5. NH₄HSO₄
6. Ba(NO₃)₂

5.

1. State Avogadro’s hypothesis
2. 0.6g of gaseous fluoride is found is occupy 112cm³ at STP. Calculate the relative molecular mass of the fluoride
3. 3.5g of hydrated salt, MSO₄ x H₂O was heated to a constant mass of 3.21g of hydrous salt of anhydrous salt. Calculate the value of (M=63.5, S=32, O= 16, H=1)

6. Soap solution of different amount of water are tested from four different sources and produces lather observed for 30 seconds. The three groups of water were untreated, Boiled and Treated by ion exchange. The results were as follows.

Use above results to answer question that follow

1. Which is hardest water sample? Why
2. Which sample is like distilled water. Explain
3. Which chemical substance might cause hardness is (i)Simple A sample B?
4. Write an equation for reaction of removing hardness in sample C

7. (a) Define chemical equation and give two importance’s

(b) Write product and balance the following chemical equations

1. AgNO_3(aq) + NaCl_(aq) →
2. Zn_(s) + H₂SO_{4 (aq)} →
3. MgCl_2(aq) + AgNO_3(aq) →
4. ZnCO_3(s) + HCl_(aq) →
5. Na_(s) + H₂O_(i)→

8. (a)List down three(3) sources of Natural water

(b)Explain why water is Not used to extinguish classic E fires

(c)Give reason to Support the fact

1. Water is Universal Solvent
2. Oxygen is collected over water
3. Oxy-hydrogen used in welding

SECTION C (30 Marks)

Answer Any two Questions

9. (a)Define molecular and Empirical formula

(b)A compound oxygen M is composed of 52.2% carbon, 13% hydrogen and the rest Oxygen. If molecular mars of M is 4

1. Find empirical formula of the compound
2. Find its molecular formula

10. With aid of diagram illustrate/Describe sit methods of separating mixtures

11. Most areas in Dar es Salaams have problem of water hardness which affect much of their life. As an expert explain how you can help them solve the problem

 THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT 

 COMPETENCY BASED SECONDARY EXAMINATION SERIES 

032/1 CHEMISTRY FORM THREE

TIME: 2 HOURS   NOVEMBER 2022

INSTRUCTIONS

1. This Paper Consists of Sections A,B nd C
2. Answer all questions in section A and B and only one(1) question from section C
3. Cellular phone and any unauthorized material are not allowed in examination room
4. Write your Examination Number on every page of your answer sheet(s).
5. The following constant may be useful
   • Atomic masses H=1, C=12, N=14,O=16,Na=23,Mg=24,S=32,Cu=64.
   • Avogadro’s number = 6.02 6.02 x 10 ²³
   • G.M.V at S.T.P = 22.4dm ³
   • 1Faraday = 96500coulombs
   • 1litre = 1dm³ = 1000cm ³

SECTION A. (20 MARKS)

1. For each items (i)-(x) choose the correct answer among the given alternative and write the letter beside the item number in the booklet provided

(i) Which of the following is the agricultural product made by the application of chemistry?

1. Yeast D. Pesticide
2. Drug E. Cement
3. Clothes

(ii) When methane undergo substitution reaction with excess chlorine .what is the end product

1. Chloromethane D. Monochloromethane
2. Dichloromethane E. Tetra chloromethane
3. Dichloromethane

(iii) An element X is found in period 4; group II of the periodic table .if the element X Undergo the reaction X→X ²⁺ +2e ^- ; the electronic configuration of X ion formed will be A. 2: 8:6 B. 2:6 C. 2:8:4 D. 2:8:8:2 E. 2:8:8

(iv) A current of 0.2A was passed through an electrolyte for 16 minutes and 40 seconds .what is the quantity of electricity produced in coulombs.

A. 2000C B. 1000C C. 200C D. 0.2C E. 7686C

(v) Which carbonate is the most stable to heat?

1. Calcium carbonate D. Zinc Carbonate C. Lead II carbonate E. Iron carbonate
2. Copper II carbonate

(vi) Skin injury that cause a change in the colour of skin

1. Bruises B. Bum C. Scalds D. Shock E. Suffocation

(vii) A good fuel is the one which has.

1. High speed of continuous energy supply D. High carbon dioxide production
2. High energy value supplied E. High content of non-combustible materials
3. Low carbon dioxide production

(viii) The region of the atmosphere which contains the ozone layer is called

1. Mesosphere D. Troposphere
2. Stratosphere E. Metamosphere
3. Atmosphere

(ix) Aluminum is said to be amphoteric oxide because

1. It acts as an acid and also It acts as a base
2. It acts as a neutral compound
3. It acts as strong reducing agent
4. It acts as a basic compound

(x) The main impurities in Nitrogen gas prepared in the laboratory are:-

1. Water vopour D. Dust particles
2. Oxygen E. Noble gases
3. Carbondioxide

2. Match the item in LIST A with a correct response in LIST B by writing the letter of the response below the corresponding item in the table given 

SECTION B. (70MARK)

Answer All questions in this section

3. (a) A stone is said to be a good example of matter. Give two reasons to support this fact.

2. Outline two significance of chemical symbols of an element.
3. Explain by giving reasons why:
   1. Laboratory door open outwards
   2. Laboratory floor is rough and never polished
   3. Fume chamber is important in chemistry laboratory

4. (a) Identify the substances by using the following information.

1. A solid is yellow when hot and white when cold
2. A colorless gas turns a yellow acidified potassium dichromate paper to green
3. When water is added to a white powder, the white powder changes to blue crystals

2. With the aid of an equation in each case, explain what will be observed when
   1. Chlorine gas is bubbled through a solution of iron II chloride
   2. Hydrogen Chloride gas is passed through a jar containing ammonia gas.
   3. A piece of sodium metal is dipped into a beaker of water containing some red litmus paper
   4. Carbondioxide is blown into a test tube filled with lime water.

5. (a) outline three reasons to explain why Carbondioxide is used to extinguish fir

(b) A sample of mass 28.6g of hydrated sodium carbonate ( Na ₂ CO ₃ .10H ₂ O) was heated such that; its water was entily absorbed by 32g of anhydrous copper II sulphate to form a blue compound of hydrated( CuSO ₄ .XH ₂ O) .find the value of X in the copper sulphate.

6.(a)A student aimed to prepared a gas X by reacting a moderate reactive metal with a dilute acid .use this information to answer the following question

1. What is the name of the gas X
2. What is the test of the gas X
3. With reasons; state the appropriate method of collecting gas X
4. Write the balanced chemical equation for the reaction.

(b) State four properties that make Aluminium useful in overhead cables

7. (a) Calculate the morality of 5% by weight of a solution of sodium hydroxide

(b) What is the simplest chemical formula of a compound formed when 36g of Magnesium combine with 14g of Nitrogen?

8.. (a) During electrolysis of an aqueous solution of salt of metal M , a current of 2.0A was passed for 32minutes and 10 second .the mass of metal M deposited was 2.24g.

1. On which electrode was the metal deposited
2. Calculate the amount of charge needed to deposit 1mole of metal M
3. Calculate the charge carried on the ion
4. Write an ionic equation to show how the ion of metal M are discharged at the electrode (R.A.M of metal M is 112)

(b)During electrolysis of brine .Sodium is deposited at the cathode and chlorine gas is released at the anode .if 2.0g of sodium are collected at the cathode .find the volume of chlorine released at S.T.P.

9. (a) State the le-chatelier’s principle

2. State what will happen in the process of equilibrium involving the equation

2SO ₂ (g) + O ₂ (g) ?? 2SO ₃ (g) ?H = -94.4KJMol -1 If

1. Temperature is lowered
2. Pressure is increased
3. The concentration of SO 3 is removed from the system.

(c)Briefly write one application of le- chatelier’s principle.

9. (a) States any three main physical properties of water and show the usefulness of each property

(b)During large – scale treatment of water, what two chemical are added at various stage?. Explain their use.

10. (a) i. Extraction of metal is said to be reduction process. Explain

ii. Why Sodium is collected by upwards in the down cell?

(b) Describe the use of each of the following during extraction of sodium

1. Calcium chloride
2. Steel gauze

2. Name the ores commonly used in the extraction of iron metal

11. (a)State the modern periodic law

(b)Study the periodic table below then answer the questions that follow.

Write the formula of compounds formed when element

1. U and W combine together
2. Q and W combine together

Draw and write electronic configuration of Y.

12. (a)Catherine is planning to make fire for cooking ugali for her family. What are necessary conditions which must be present so that she can make fire successfully for cooking ugali for her family?

(b)Give a reason for each of the followings

1. Water is universal solvent
2. Some metal like zinc do not get rust.
3. Chlorine gas is collected by downward delivery
4. Carbon dioxide turns lime water into milky colour.

SECTION C (15 MARKS)

Answer only one (1) question.

13. (a)Give good reason (s) for the following. (Answer according to the question demand).

1. Natural gas is so popular in heating and cooking in homes. (2 points)
2. Nuclear energy is not a sustainable source of energy. (2 points)
3. Coal and petroleum are non-renewable sources. (1 point)

(b) State the main raw materials and process involved in the manufacture of each of the following products.

1. Wood charcoal
2. Coke
3. Lamp black
4. Animal charcoal

14. (a) 25cm ³ of 0.1MHCl were neutralized by 23cm ³ of Na ₂ CO ₃ solution. Calculate the concentration of the alkali in grams per litre.

(b)Suggest a suitable indicator of each of the following titrations

1. Hydrochloric acid against ammonia solution
2. Sulphuric acid against sodium hydroxide solution
3. Ethanedioic acid against potassium hydroxide solution

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

COMPETENCE BASED SECONDARY EXAMINATION SERIES

CHEMISTRY TERMINAL EXAMINATION

FORM THREE-2022

Time: 3 Hours

Instructions.

1.    This paper consists of section A, B and C with a total of 14 questions
2.    Answer all questions in section A and B and ONE (1) question from section C.
3.    Section A and C carries 15 marks, while section B 70 marks
4.    Cellular phones and any unauthorized materials are not allowed in the examination room.
5.    Non programmable calculators may be used.
6.    Write your number on every page of your answer booklet.
7.    Where necessary the following constants may be used;

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.

1. Chemistry is a study of

1.              The chemicals used in the laboratory
2.               An experiment carries out in industries.
3.               The composition , structure and properties of matter
4.              All scientific processes.

2. Hassan wants to grid the granules of a certain chemical to fine powder. The apparatus he will use include a.

1.              Pestle and filter funnel
2.               Round-bottomed flask and trough
3.               Mortar and pestle.
4.              Bunsen burner and filter paper.

3. Which of the following is a physical change?

1.              Milk left on the counter turns sour
2.               Common salt dissolves complete in water
3.               A forest fire burns all the trees
4.              Fruits are fermented to produce wine

4. When a substance is heated and change from solid directly to a vapor the process is called

1.              Condensation
2.               Dissolving
3.               Sublimation
4.              Melting

5. Which of the following gases if mixed with Hydrogen produce a very hot flame of up to 3000^oC.

1.              Oxygen
2.               Neon
3.               Chlorine
4.              Argon.

6. An isotope of Cadmium has an atomic number of 48 and mass number of 112. This mean that the Cadmium atom has.

1.              48 protons, 64 neutrons, 48 electrons
2.               64 protons, 48 neutrons, 64 electrons
3.               48 protons, 112 neutrons, 48 electrons
4.              112 protons, 112 neutrons, 112 electrons

7. The reaction between Silver nitrate and Sodium chloride to form Silver chloride and Sodium nitrate is an example of a ………………. Reaction.

1.              Direct combination
2.               Simple displacement
3.               Double displacement
4.              Decomposition.

8. Which of the following pairs of oxide are gaseous at room temperature?

1.              Carbon dioxide and copper (II) oxide
2.               Sulphur dioxide and copper (II) oxide
3.               Carbon dioxide and Sulphur dioxide
4.              Copper (II) oxide and Iron (II) oxide

9. Ammonium chloride reacts with sodium hydroxide solution on warming. The net ionic equation for the reaction is.

1.              H⁺_(aq) + OH^-_(aq) → H₂O_(l)
2.               NH⁺_(aq) + OH^-_(aq) → NH_3(aq) + H₂O_(aq)
3.               Na⁺_(aq) + Cl^-_(aq) → NaCl_(aq)
4.              2NH₄⁺_(aq) + 2Cl^-_(aq) → NaCl_(aq) + Cl_(g) + H_2(g)

10. Which of the following is not a property of Hydrogen gas?

1.              It support combustion
2.               It is slightly soluble in water
3.               It is less denser than air
4.              It is colorless and odorless

2. The following are the matching items .Match the correct item in LIST B corresponding one from LIST A. Write the letter in answer sheet provided.

SECTION B ( 70 Marks)

Answer all questions in this section.

3.                a) i. What is an air?

    ii. Is air a compound or mixture? Give four (4) reasons to support your answer.

b) State the methods of separating the following mixture. Give a reason to support your answer.

1. Kerosene and water
2. Muddy water
3. Ethanol and milk.

4.                a). Define the following terms

1. First Aid
2. First aid kit.

b) Give five (5) items found in the First aid kit and their uses.

c) What First aid do you give to a person who has fainted?

5.                a) Differentiate between the following terms.

1. Chemical reaction and chemical equation.
2. Reactants and products
3. Displacement reaction and Double displacement reaction.

b) Complete and balance the following reaction.

1.              +                   → Mg(NO₃) _(aq) + Zn_(s)

2. Pb(NO₃)_{2 (s)} + Na₂SO_{4 (aq)} →

3. Pb(NO₃)₂ (s)         Heat

6.                a) Explain the meaning of the following terms.

1. Mole
2. Molarity

b) i. State the Avogadro’s law.

ii. Mention two (2) applications of Avogadro law

7.                a) By using a well labeled diagram explain the preparation of oxygen using hydrogen peroxide.

b) List three chemical properties of oxygen.

8.                a) Name the following compounds according to the IUPAC system of nomenclature

1. Fe₂(SO₄)₃
2. KMnO₄
3. H₂SO₄

b) What is fuel? 

c) State four (4) the characteristics of good fuel.

9.                a) Define

1. Atom
2. Isotopes

b) i. What is an electronic configuration? 

ii. Give three (3) applications of electronic configuration.

10.             a) Distinguish between the following terms

1. Corrosive and irritant
2. Radioactive and explosive
3. Solution and suspension

b) i. What is flame?

ii. Differentiate between luminous and non-luminous flame. Give four (4) points. 

11.            a) Explain the meaning of the following terms

1. Empirical formula
2. Molecular formula

2.                The compound of carbon and hydrogen has the empirical formula CH₃. Find its molecular formula if its relative molecular mass is 30 (r.a.m carbon = 12).

12.            a) State four (4) natural sources of water.

b) Explain four (4) economic importance of water.

SECTION C (  15 Marks)

Answer one (1) question from this section.

13.            a) Explain the meaning of  each of the following terms

1. Concentration of the substance
2. Molar mass
3. Stoichiometry

b) Calculate the number of moles in each of the following substances

1. 1.064g of Magnesium nitrate
2. 1.397g of Copper (II) sulphates
3. 3.67dm³ of Sulphur dioxide at s.t.p

c) Calculate the number of ions present in 30g of Aluminum sulphates.

14.  With the aid of a chemical equation, describe how you would prepare pure solid sodium chloride by the action of an acid and a base.

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

COMPETENCE BASED SECONDARY EXAMINATION SERIES

CHEMISTRY MID TERM EXAMINATION

FORM THREE-MARCH/APRIL-2022

Time: 3Hours

Instructions.

1. This paper consists of section A, B and C with a total of 14 questions
2. Answer all questions in section A and B and ONE (1) question from section C.
3. Section A and C carries 15 marks, while section B 70 marks
4. Cellular phones and any unauthorized materials are not allowed in the examination room.
5. Non programmable calculators may be used.
6. Write your number on every page of your answer booklet.
7. Where necessary the following constants may be used;

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 in the table provided
   1.      Kinetic nature of matter describe

1. The shape of three states of matter
2. The movement of particles in the three state of matter
3.  The process of treating solid, liquid and gas
4. Describe the meaning of matter
5. Make up of matter

2.  Nitrogen (III) oxide has a formula

1. N₂ O₅
2. NO₃
3. NO₂
4. N₂ O₃
5. N₃O₂

3.                           A pair of the following substances from a miscible liquid

1. Paraffin and water
2. Paraffin and benzene
3. Water and glycerin
4. Water and kerosene
5. Water and milk

     (vi)        Which one of the following sets of elements is arranged in order to increase  

            electro negativity starting with the least one?

1. Chlorine, fluorine, nitrogen, oxygen, carbon
2. Fluorine, chlorine, oxygen, nitrogen, carbon
3. Carbon, nitrogen, oxygen, chlorine, fluorine
4. Nitrogen, oxygen, chlorine, carbon, fluorine
5. Nitrogen, oxygen,sodium, carbon, fluorine

5. “Striking back” means

1. Luminous flame
2. Flame burning inside the barrel when the air hole is open
3. Non-luminous flame
4. Flame burning inside the barrel when the air hole is closed
5. Excess gas
   6. Element Q of atomic number 15 is found in
6. Group V and period 3
7. Group I and period 2
8. Group III and period 4
9. Group IV and period 1
10. Group 15 period 5

7. Which of the following natural processes is not a chemical change?

1. Photosynthesis
2. Respiration
3. Rain formation
4. Corrosion of iron
5. Souring of milk

8.  This mixture of substances can extinguish fire

1. Oxygen and nitrogen
2. Carbon and sand
3. Carbondioxide and hydrogen
4. Carbondioxide and sand
5. Hydrogen and oxygen

9.   The physical test for oxygen is

1. Support the burning splint
2. Colourless, no smell and tasteless
3. Produces “POP” sound
4. Turns lime water blue
5. Has sweet aroma

10.        An element ‘A’ of element configuration 2:8:3 combines with an element ‘B’of configuration 2:6. The chemical formula of the compound is 

1. B₆ A₃
2. A₃ B₆
3. A₂ B₃
4. A₃ B₂
5. B₂A₃

SECTION B.

2.  Match the item in list A with the responses in list B by writing the letter of the correct response in list the box below.

List A.

1. Octet state
2. Fossil fuels
3. Rusting of iron
4. Desiccators
5. Solvent extraction

      List B.

1. Hardening of oil
2. Aqueous
3. Full of eight electrons in the outermost shell
4. Water and kerosene
5. Inert state
6.  Electronic configuration
7. Coal, natural gas
8. Used to obtain oil from groundnuts
9. Potassium, sodium
10. Enzymes
11. For drying substance
12.  Condensation
13. Ionic equation
14. Catalyst
15. Chemical change
16. Physical change

SECTION B (70 Marks) 

Answer all questions in this section

3.  (a) Define the following terms:
   1. Fuel ……………………………………………………………………………………………………………………………………………………
   2. Calorific value of a fuel ……………………………………………………………………………………………………………………………………………………
   3. Energy value of a fuel ……………………………………………………………………………………………………………………………………………………

(b) Give two examples of each of the following:

(i) Solid fuel ………………………………….., ……………………………..

(ii) Liquid fuel…………………………………..,……………………………...

(iii) Gaseous fuel ……………………………….., …………………………….

(c) Name four characteristics of a good fuel 

(i) ………………………………………………………………………………

(ii) ………………………………………………………………………………

(iii) ……………………………………………………………………………..

(iv) ……………………………………………………………………………..

4. (a) Water is said to be a compound. Verify this statement
   1. …………………………………………………………………………
   2. ………………………………………………………………………….
   3. ………………………………………………………………………….
   4. ………………………………………………………………………….

(b) Study the apparatus arranged below and answers the questions below.

1. Name the apparatus labeled

1. ……………………………………………………………………
2. ……………………………………………………………………
3. …………………………………………………………………..

E…………………………………………………………………..

2. What is the function of the apparatus labeled E? …………………………………………………………………………
3. What is the role of manganese (IV) oxide (MnO₂) in the above experiment? ………………………………………………………………………......
4. How can you test the presence of oxygen …………………………………………………………………………..
5. What was the aim of the above experiment? …………………………………………………………………………..
6. Write a balance chemical equation of the reaction which occurred in apparatus C above …………………………………………………………………………

5. (a) (i) Define valence ………………………………………………………………………………………………………………………………………………………………………………

(ii) Write down the valence of the following elements: 

Magnesium …………………………………. Lithium ……………………………

(iii) Name the following radicals and state their valences

(b) Write the following compounds 

(i) Aluminium oxide ………………………………………………………………

(ii) Lead (II) nitrate ……………………………………………………………..…

(iii) Ammonium carbonate …………………………………………………………

(iv) Lead (II) sulphide ……………………………………………………………..

(v) Copper (II) hydroxide …………………………………………………………

6. (a) Define:
   1. Empirical formula ……………………………………………………………………………………………………………………………………………………
   2. Molecular formula ……………………………………………………………………………………………………………………………………………………

(b) A certain gaseous compound contains 82.8% of carbon and 17.2% of hydrogen by mass. The vapour density of the compound is 29. Calculate its molecular formula (C = 12, H = 1)

7. (a) By giving one example define the following terms
   1. Suspension ……………………………………………………………………………………………………………………………………………………
   2. Electroplating ……………………………………………………………………………………………………………………………………………………
   3. Galvanizing ……………………………………………………………………………………………………………………………………………………
   4. Element …………………………………………………………………………………………………………………………………………………….
   5. Matter ……………………………………………………………………………………………………………………………………………………

(b) Give four uses of hydrogen gas 

(i) ……………………………………………………………………………….

(ii) ………………………………………………………………………………

(iii) ……………………………………………………………………………..

(iv) ……………………………………………………………………………..

8. (a) What do you understand by the term isotope? ………………………………………………………………………………………………………………………………………………………………………………

(b) Chlorine has two isotopes of chlorine – 35 ³⁵₁₇ Cl, which constitutes of 75% in the mixture and chlorine – 37 ³⁷₁₇ Cl, which constitutes of 25%. Calculate the relative atomic mass of chlorine. 

 (c) One of the methods of preventing iron from rusting is sacrificial protection,   

                  why it is called so  ……………………………………………………………………………………………………………………………………………………………………………………

      9. (a) Give the meaning of the following terms 

     (i) Solution ……………………………………………………………………………..

     (ii) Emulsion …………………………………………………………………………… 

               ……………………………………………………………………………………

     (iii) Potable water ………………………………………………………………………

              …………………………………………………………………………………….

      (b) State the modern periodic table     

………………………………………………………………………………………………………………………………………………………………………………………………

        (c) Name heat sources used in the laboratory 

        (i) ………………………………………………………………………………

        (ii) ……………………………………………………………………………..

        (iii) ……………………………………………………………………………

        (iv) …………………………………………………………………………… 

     10. (a) Show how the following change in the periodic table:

      (i) Electronegativity ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(ii) Ionization energy ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(iii) Atomic size ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(b) “Chemistry is the useless subject” Discuss the above statement with reasons

(i)……………………………………………………………………………………………      

     …………………………………………………………………………………………

(ii) …………………………………………………………………………………………..

     …………………………………………………………………………………………..

(iii) …………………………………………………………………………………………

      ………………………………………………………. ………………………………..

(iv) …………………………………………………………………………………………

      …………………………………………………………………………………………

11.      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.

12.   Balance the following equations: 

  (i)Ca + H₃PO₄→ Ca₃(PO₄)₂ + H₂

2.                      Cu + HNO3 → Cu (NO3 )₂ + NO2 +H20
3.                      SnCi₂+FeC1₃→SnC1₄+FeCI

13.     Give the name of the types of reaction represented by each of the following chemical equations.

1.                      C₃H_8(g) +50,₍₀₎→ 3CO2 + 4H₂0₍₁₎
2.                      2Pb (N 0₃),₍,₎→2Pb0₍,₎ + 4NO2 +0_2(g)

(iii)Zn(s)+CuS0_4(aq) —>ZnSO_4(aq) +CU(S)

14.     Complete the following equations and determine the type of chemical reaction involved in each case.

(i) Zn(s)+ H₂SO_4(aq)→

(i) AgN 03_(aq) + NaCl_(aq)→

(iii) N_2(g) + H_2(g) →

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES

CHEMISTRY    ANNUAL   EXAMINATION

FORM THREE-NOVEMBER 2021 

Instructions

1.                This paper consists of sections A, B and C with a total of fourteen (14) questions.
2.                Answer all questions in sections A and B and one (1) question from section C.
3.                Sections A and C carry fifteen (15) marks each and section B carries seventy (70) marks.
4.                Cellular phones and any unauthorised materials are not allowed in the examination room.
5.                Write your Examination Number on every page of your answer booklet(s).
6.                The following constants may be used.

 H 1,    C = 12,  0=16,    N = 14,  Cu = 64,   Pb = 108.

                  A vogadros 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 (20 Marks) 

Answer all questions in this section.

1. For each of the items (i) (x), choose the correct answer from the given alternatives and write its letter beside the item number.

 (i) Which of the following is an agricultural chemical products made by the application of chemistry?

1.              Drugs           
2.              Pesticides        
3.              Clothes 
4.              Yeasts 
5.               Cement.

 (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?

1.               2000 C  
2.              1000 C 
3.               200 C 
4.               0.20 C 
5.                7686 C.

(iii) Substance X liberates chlorine gas from acidified potassium chloride. The behaviour of X is described as:

1.   an oxidising agent    
2.   an oxidising and reducing agent
3.   catalyst   
4.   a reducing agent
5.   bleaching agent.

(iv) Which carbonate is the most stable to heat?

1.               Calcium carbonate   
2.               Copper (II) carbonate
3.               Lead (II) carbonate 
4.               Zinc carbonate 
5.               .Iron (II) carbonate.

(v)  Aluminium does not react with water and does not corrode much in air because

1.               it is below hydrogen in the reactivity series
2.               it forms a stable carbonate which prevents reactions
3.               the metal is covered with a protective coating of an oxide 
4.               aluminium ions have positive charges
5.                it is very stable.

(vi) Which of the following compounds does NOT belong to the alkenes homologous series?

1.               C₂H₄ 
2.               C₃H₆  
3.               C₄H ₈ 
4.               C₅H₁₀ 
5.                C₆H ₁₄.

(vii) In the following equilibrium equation, 2S0_2(g) +O_2(g)  2S0₃ The forward reaction is exothermic. Which change would increase the production of sulphur trioxide at equilibrium?

1.               Increasing temperature
2.               Decreasing temperature
3.               Decreasing sulphur trioxide concentration 
4.              Decreasing pressure 
5.               Adding a catalyst.

(viii) When a burning fuel produces blue color it means there is

1.    adequate supply of oxygen with production of soot.
2.     inadequate supply of oxygen without production of soot. 
3.     inadequate supply of oxygen with production of soot.
4.     adequate supply of oxygen with production of less heat.
5.      adequate supply of oxygen with production of more heat.

(ix)  Which of the following equations represents the combustion of methane with the products collected at 120^oC?

1.               CH4(l) +2O2(g) →CO2(g) + 2H2O(l)
2.               CH4(g) +2O2(l) →CO2(s) + 2H2O(l)
3.               CH4(g) +2O2(g) →CO2(g) + 2H2O(g)
4.               CH4(l) +2O2(l) →CO2(l) + 2H2O(g)
5.                CH4(l) +2O2(g) →CO2(g) + 2H2O(g)

   (x) Which of these can be reduced when heated with carbon?

1.               Aluminium  
2.              Calcium carbonate
3.              Iron (III) oxide 
4.              Magnesium oxide 
5.                Sodium oxide.

2.   Match the items in List A with the responses in List B by writing the letter of the correct response beside the item number in the answer booklet provided. Match the items in List A with the responses in List B by writing the letter of the correct            

SECTION B (70 Marks)

Answer all questions in this section.

3. (a) Define the following terms: 

1. Neutralization.
2. Unsaturated solution.
3. Thermal decomposition.

(b) State three main physical properties of water and show the usefulness of each property.

(c)   State three industrial application of electrolysis.

4.   (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

5. (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.

6.  (a) Give one example in each of the following:

 (i) Alkali earth metals.

(ii)  Noblegases .

(iii) Transition elements.

(b) Write the names of the following processes of changing matter from one state to another.

(i) Gas to liquid. 

(ii) Ga s to solid. 

(iii) Solid t o gas .

7 (a) Define the following:

   ( i ) Mole .

 ( i i ) Molarmass .

(b) 112 dm³ of oxygen gas was collected at s.t.p when a sample of lead nitrate was completely decomposed by heat. Calculate the volume of nitrogen dioxide gas produced.

8. (a)   Identify and state the environmental problem caused by the gas which is released from the blast furnace in the extraction of iron from its oxide.

(b)  The following equation shows the reaction between hydrogen and iodine gas to form hydrogen iodide gas,H_2(g)  + I_2(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.

9.  (a) Name two elements which are expected to show similar chemical reaction with magnesium. What is the basis for your choice?