THE PRESIDENT’S OFFICE
REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
BRIGHT EDUCATION DEVELOPMENT ACADEMY - KIVULE
FORM THREE MONTHLY TEST
CHEMISTRY 032
TIME: 2 HOURS, 06 February 2023
INSTRUCTIONS
Answer all questions in all sections
All answers must be in blue or black ink except drawings which must be in pencil.
Write your examination number on every page of your answer sheet.
Non-programmable calculators and mathematical tables may be used.
You may use the following constants;(i)Atomic masses; C = 12, H=1, Cl=35.5, Na=23, O=16, Zn=65, Ca=40, Cu=64,S=32, Fe=56, Al=27.
(ii)GMV at STP = 22.4dm3.
(iii)1 Faraday = 96,500 Coulombs.
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 answer sheet provided.
(i) Which of the following statements is correct about oxidation
A. Removal of hydrogen
B. Removal of oxygen
C. Oxide
D. Hot gas
E. Fire
(ii) The reaction that proceeds in either direction is called;
A. redox reaction
B. combustion reaction
C. directional reaction
D. reversible
E.irriversible
(iii) A solution of pH 1.6 is best described as
A. Strong acid
B. Weak base
C. Weak acid
D. Strong base
E. Neutral solution
(iv) An element losses or gains electrons to form
A. Ions
B. Molecules
C. Isotopes
D. Allotropes
E. Radicals
(v) A substance which absorbs water from the atmosphere and form a solution is called
A. Efflorescent
B. Hydroscopic
C. Deliquescent
D. Amphoteric
E. Hydrological
(vi)0.5g of hydrogen gas is exploded in air to produce water. The mass of water formed is;
A. 1.8
B. 4.5
C. 0.75
D. 18g
E. 45g
(vii)The oxidation number of phosphorus in the radical PO43- is;
A. +3
B. +5
C. -3
D. -5
E. 4
(viii) The magnesium salt responsible for permanent hardness of water is;
A. Hydrogen carbonates
B. Sulphate
C. Nitrate
D. Carbonate
E. Chloride
(ix)A rapid chemical reaction that releases energy in form of light and heat is called:
A. Combustion
B. Decomposition
C. Displacement
D. Neutralization
E. Precipitation
(x)The following are methods used to soften permanent hard water except;
A. ion exchanger
B. boiling
C. adding washing soda
D. distillation
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2. Match the descriptions in LIST A with corresponding responses in LIST B by writing the letter of correct response beside the item number in the answer sheet provided.
LIST A |
LIST B |
(i)Decomposition reaction. (ii)Displacement reaction (iii) Net ionic equation (iv) Complete ionic reaction. (v)Spectator ions. |
A. Shows only chemical species that involved in the reaction B. F2 + 2HCl→2HF + Cl2 C. Complex chemical compounds broken into simple molecules. D. Found both sides of the chemical equations. E. Both spectator ions and reacting species are included. F. Only hydroxide ions and hydrogen ions are involved. G. 2H2(g)+O2(g)→2H2O(l)
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LIST B |
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SECTION B (70 Marks)
Answer all questions in this section
3. During chemistry practical session a form two students was instructed to prepare a certain gas whose reaction equation was as shown below;
(a) (i) What is the purpose of MnO2 in the reaction?
(ii) What will happen to the rate of reaction if MnO2 is not used in the above reaction?
(b) Briefly explain how the gas produced from the reaction is tested?
(c) Give three ways in which the gas prepared above is useful in daily life.
4. (a) Define the following terms;
(i) Mole
(ii) Molar mass
(b) 112dm3 of oxygen gas was collected as S.T.P when a sample of Lead nitrate was completely decomposed by heat. Calculate the volume of nitrogen dioxide produced.
5. (a) (i) What is dilution factor
(ii) Give the dilution formula
(b) Nelson wants to prepare a solution whose concentration is 0.5M from 500cm3of 3M Sulphur acid. To what volume should he dilute the acid?
6. (a) Explain the meaning of molar volume of a gas.
(b) If 0.5g of hydrogen gas is exploded in air, what is the mass of water formed?
7. (a) How many moles of oxygen atoms are there in 0.5moles of Sulphur dioxide (SO2)?
(b) Calculate the number of ions present in 20g of Aluminum sulphate.
8. (a) A form three student conducted an experiment in the laboratory to synthesize nitrogen,dioxide, ammonia and Ethane. The experiment results were tabulated as;
Experiment |
Reagents |
Conditions |
Products |
1 |
Copper (II) nitrate |
Heat |
Copper (II) oxide, oxygen gas and nitrogen dioxide gas.
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2 |
Gaseous hydrogen and gaseous nitrogen |
Catalyst |
Ammonia gas |
3 |
Ethyne gas and hydrogen gas |
Catalyst |
Ethane |
Write the word equations to summarize the reactions taking place in experiment 1 to 3.
(b) Write the ionic equations for the following chemical reactions.
(i) HCl(aq) + NaOH(aq)→NaCl(aq) + H2O
(ii) AgNO3(aq) + HCl(aq)→AgCl(s) + HNO3(aq)
SECTION C:15 MARKS
9. Three students from Mtakuja Secondary school performed an experiment to determine the hardness of water by using soap and the following water sample.
Water sample: A = Water from Lembeli
B = Water from Machinjioni
C = Water from Uswahilini
D = Water from Mjini A
SAMPLE |
VOLUME OF SOAP USED (cm3) |
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Untreated water |
Boiled water |
Water passed through the ion exchanger. |
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A |
12 |
1.8 |
1.8 |
B |
17 |
17 |
1.7 |
C |
26 |
20 |
1.8 |
D |
1.6 |
1.6 |
1.6 |
(a) Which water sample is hardest? Give a reason for your answer.
(b) Which sample behaves as distilled water? Explain
(c) Name a chemical substance that cause hardness in;
(i)Water sample A
(ii)Water sample B
(d) Which problems may people from Lembeli, Machinjioni and Uswahilini face when they use water from their living place?
10. Give four advantages of hard water and five disadvantages of hard water
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Marking scheme