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 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

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 1 MID TERM EXAMINATION

FORM THREE-2021

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 (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.

1. The region around the nucleus of an atom where electrons are found is called:-

1. Shell (orbits or energy levels)
2. Solar or Lunar eclipse                                
3. Ozone layer
4. Outer most shell.

1. The following is a chemical property of oxygen.

1. It burns completely when exposed and produce a “pop sound”.
2. It supports combustion .                            
3. It produces unpleasant smell
4. It reacts with vapour to form carbon dioxide gas.

1. _________ is one of the use of hydrogen 

1. it is used by mountain climbers
2. it is used in painting
3. it is used in manufacturing of ammonia       
4. it is used for breathing.

1. A special catalyst used in the laboratory preparation of oxygen gas by using potassium chlorate (KClO₃) is:-

1. Manganese (IV) oxide
2. Zinc granules                                                 
3. Anhydrous copper (II) sulphate
4. Gas jar

1. Which of the following chemical species have the same number of electrons?

1. Cl, Be and O^2-
2. K+, Ca²+, Cl^-  
3. O^2-, Ca²⁺ and  Ar                                     
4. Na⁺, Mg^2+, Be²⁺ and Li.

1. Match each item in list A with response in list B by writing its correct letter to the number of the corresponding item in the table provided below.

SECTION C (70 MARKS)

           Questions:-

______________________________________________________________________________________________________________________

(b) Write the chemical symbols for the following elements:-

(i) Magnesium________ (ii) Tin _______(iii) chromine_____    (iv) Lead______

(c ) For each of the following chemical symbols of elements write its corresponding chemical name:-

1. Si______________        (ii) Cu____________       (iii) Mn_____________

1. The figure below is part of the periodic table which includes  the first 20 elements. Study it carefully and answer the question that follows.

Questions:-

 For each number write the chemical symbol of the corresponding element

1. Write the formula which represents a compound formed between an element with atomic number 1 and element with atomic number 17. ___________
2. Considering the elements with atomic number 12 and 17, which is a metal and which is a non – metal?

1. Write the number which represent an element with a property of burning in oxygen to form waters________________________
2. Write the number which represent and element with inert property._________

1. (a) Define the following

1. Empirical formula
2. Molecular formula 

(b) 0.7g of nitrogen combines with 1.6g of oxygen to form a nitrogen oxide. Given the molecular mass of a compound is 92.

Calculate: (i) The empirical formula

       (ii)The molecular formula

            (Use atomic masses  N= 14, O= 16). 

              (ii Write a chemical formula for water_______________

(b) (i) What is a fuel?_____________________________________________

(ii) Give two examples for each of the following categories of fuels in terms of their states of matter

Solid fuels_____________________________________________________

Liquid fuels_____________________________________________________

Gaseous fuels__________________________________________________

6. (a) Define the term a chemical equation. 

(b) Write down components of a chemical equations list only three (3). 

(c) Balancing the following chemical equations;

1. Al(NO₃)₃(_aq) + 3NaOH_(aq)                      Al(OH)_3(s) + NaNO_3(aq) 
2. Ba(NO₃)_2(aq) + (NH₄)₂SO_4(aq)                   BaSO_4(s) + NH₄NO_3(aq)
3. CaCl₂(aq) + Na2CO_3(aq)                      NaCl_(aq) + CaCO_3(s) 
4. Zn(NO₃)_2(aq) + Na₂S_(aq)                    NaNO_3(aq) + ZnS_(s)  
5. Na₂CO_3(aq) + HNO_3(aq)                    NaNO_3(aq) + H₂O_(l) + CO_2(g)

7. (a) Give the IUPAC names for each of the following compounds:-

1. Cu₂O______________________(ii)Na₂SO_{4_________________________________}
2. Fe₂O₃__________________________

(b) Calculate the oxidation number of underlined elements:-

(i) CO^2-            (ii) HCO₃                                          (iii) KClO₃

(c) Write the electronic configuration of Cl^-  and hence draw its electronic diagram^.

8. Explain the meaning of each of the following types of chemical reactions and support your explanation with the help of a relevant chemical equation.

1. Synthesis (combination) reaction
2. Decomposition reaction
3. Precipitation reaction
4. Single displacement reaction
5. Neutralization reaction 

1. Soap solution of different amount of water are tested from four different sources and produces lather observed for 30 seconds. The three groups of waster were the untreated; boiled and treated by ion exchange. The results are as follows;

                Use the above results to answer the following questions; 

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

10. (i) Define the following terms;

1. Soft water 
2. Hard water 
3. Permanent hardness of water 
4. Temporary hardness of water 

(ii) Explain why the ability of temporary hard water to conduct electricity falls when the water is boiled but does not fall when temporary hardness is removed by addition of washing soda.

 11. Give a brief account to the following 

1. Why does water note have any effect on litmus paper?
2. (i) What would happen to a well stoppered   bottle full of water left in a deep freezer over the night? Why does this happen?

(ii) Why is iron not usually recommended in the construction of steam pipes and boilers.

      (ii) Write one balanced chemical equation which shows how temporary hardness can be removed by boiling. Also write  one balanced equation which shows how sodium carbonate can be used to remove permanent hardness of water.

12. (a) Define the following words:-

1. Deliquescence
2. Efflorescence

(b) Give at least three (3) uses of salts

(c ) When zinc granules and dilute sulphuric acid are reacted together, gas M is produced. The gas produced is collected by downward displacement of water. Use this information to answer the questions below:-

1. Name the gas M
2. How is gas M tested?
3. Why is a the gas collected by down ward displacement of water?

SECTION C (15 Marks)

Answer one question in this section.

13. For each of the following write equations for the reactions that would take place.

1. Action of heat on Sodium nitrate, Lead (II) nitrate and mercury (II) Nitrate.
2. Action of heat on sodium carbonate and copper (II) Carbonate.

14.  (a) 416g of anhydrous barium chloride where obtained when 488g of hydrated salt were heated. 

       Calculate the value of n is the formula BaCl₂.nH₂O (Ba = 137)

(b) Give the meaning of the following;

       (i) An acid

      (ii) Molar solution of an acid 

     (iii) Give three characteristics of acid. 

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION AND LOCAL GOVERNMENT

MID TERM EXAMINATION-MARCH 2020

CHEMISTRY FORM THREE

NAME………………………………….………………..CLASS…………………………….……………TIME: 3HRS

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 : O= 16, Na= 23, S=32,H=1, K=39, Al= 27,
• GMV  at STP = 22.4dm³
• Avogadro’s constant = 6.02 x 10²³
• 1litre = 1dm³= 1000cm³.

SECTION A (15  marks)

1. Write the  letter of the correct answer in the answer sheet (s) provided for each of the following questions (i)  to (x).
2. All domestic utensils made of iron undergo rusting when exposed to:-
3. Air and fire
4. Air and oil
5. Air and water
6. Water and oil
7. When a small amount of common salt is dissolved in a glass of water the mixture formed is:-
8. Heterogeneous
9. Homogenous
10. Immiscible
11. Suspension 
12. A chemist should acquire all of the following skills EXCEPT:-
13. Experimentation
14. Observation
15. Problem identification 
16. Surgery 
17. An important property of oxygen which distinguishes it from other gases is that it:-
18. Burns and supports combustion
19. Burns but does not support combustion 
20. Neither burns nor support combustion
21. Support combustion but does not  burn
22. The process of chlorination in water treatment aims at:-
23. Forming suspension
24. Killing micro- organisms
25. Making syrup
26. Removing bad odour

1. One of the following is not correct about coke being a better fuel than coal as it:-
2. Does not produce carbon dioxide gas
3. Does not produce poisonous gas
4. Has a higher heat content
5. Is clean and smokeless
6. Class E fire can best be extinguished by using:-
7. Carbon dioxide
8. Fire blanket
9. Sand
10. Water
11. The following is a set of apparati which are used for heating:-
12. Crucible, test tube, evaporating dish
13. Evaporating dish, tongs, crucible
14. Test tube, evaporating dish, tongs
15. Tongs, crucible, test tube.
16. Which of the following methods can be used to get oil from cotton seeds?
17. Decantation
18. Distillation
19. Grinding and distillation
20. Grinding followed by squeezing 
21. Which of the following apparati is suitable for measuring volumes of smaller quantities of liquids?
22. Beaker
23. Burette
24. Conical flask
25. Measuring cylinder
26. Match each item in list A with response in list B by writing its correct letter to the number of corresponding item in the answer sheet(s) provided.

SECTION B (70 marks)

(b) Write down the names and formulae of three common acids in the laboratory.

(c ) What is an indicator? Give four (4) examples of acid- base indicators.

(d) Write down the products formed when each of following pairs of compounds react:

(i)        Acid and metal

(ii)       Acid and metal carbonate

 (b) Write a balanced chemical equation and its corresponding ionic equation for the reaction between dilute sulphuric acid and:-

1. Sodium  hydroxide solution.
2. Zinc granules.

N.B.  show all the state symbols.

(b) Calculate the molar mass of  (i) Al₂ (SO₄)₃   (ii) Na₂ CO₃ 10H₂O

( c) State the Avogadro’s law

(d) How many oxygen molecules are there in 20cm³ of oxygen gas at STP?

     (ii) Name two types of flames produced by the Bunsen burner

    (iii)How do the two above mentioned flames differ?

(b) Write down four (4) careers that are a result of studying chemistry.

              (ii)     Does Oxygen burn? Why?

1. The formula of manganese (iv) oxide is M_nO₂  and that of hydrogen peroxide is H₂O₂. Which compound produces oxygen?
2. (i) What is the name of the method of collection the gas?

(ii) Explain the meaning of catalyst.

             (iii)How can you test for oxygen?

Note: The letters used are not the scientific symbols for the elements concerned.

1. Identify and write down the electronic configuration for the elements K,N,P and L
2. What type of bond will exist in a compound formed when Q combines with L? write the chemical formula for the compound formed and list two chemical properties of the compound formed.

9.  (a) Write the chemical symbols for beryllium, boron, neon, nitrogen and phosphorus.

      (b) Why some of the elements in 9(a) are assigned symbols with only one letter while others bear symbols with two letters?

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

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) Write the IUPAC names of the following compounds 

1. NaClO₃ 
2. K1O₃ 
3. NaH
4. Ca(NO₃) 
5. NO

(b) Write the chemical formula of the following compounds 

(i) Lead (II) chloride 

(ii) Aluminium hydride 

(iii) Sodium hydrogen phosphate (v) 

(iv) Sulphur oxide (VI)

(v) Ammonium chloride

SECTION C (15 Marks)

Answer one (1) question from this section.

13. (a) Differentiate between basic salt and acidic salt.                                                

 (b) Categorize the following salts; 

       i.  PbSO₄    ii.  MgHSO₄     iii. Zn(OH)Cl   iv. MgHCO₃  

         v. NH₄HSO₄     vi. Ba(NO₃)₂ 

(c) 1.16g of magnesium was allowed to react with excess dilute sulphuric acid. What 

      volume of Hydrogen gas at STP was liberated.                                            

14. (a) Define the following;

1. Molarity 
2. Standard solution 
3. Equivalent point of titration 
4. End point                                                                                                                 

 (b) On titration 20cm³ of a solution containing 2.65g per 500cm³ of A₂CO₃, exactly 

react with 20cm³ of 0.1M hydrochloric acid solution. Write balanced equation; 

1. Molarity of A₂CO₃                                                                                                   
2. Molar mass of A₂CO₃                                                                                                                                                                    
3. Atomic mass of A                                                                                                    
4. Identify element A