CHEMISTRY THIRD TERM EXAMINATION SENIOR SECONDARY SCHOOLS (SS 2) EXAM QUESTIONS

SECTION A – OBJECTIVES

INSTRUCTION – CHOOSE THE CORRECT ANSWER FROM THE OPTIONS A – D. 

1. Which of these is a universal solvent?

(a) Benzene

(b) Phenol

(c) Kerosene

(d) Water

 

2. Treated town water undergo the following steps except ______.

(a) coagulation

(b) sedimentation

(c) precipitation

(d) chlorination

 

3. Temporary hardness of water is removed by the use of the following except ______

(a) boiling

(b) use of Ca(OH)2

(c) use of Na2CO3

(d) Use of alum

 

4. One of these is water pollutant?

(a) Petroleum

(b) Domestic liquid an solid water

(c) Industrial effluents

(d) Biodegradable chemicals

 

5. These are abnormal physical properties of water except ______.

(a) turn to ice cooled below zero degree Celsius

(b) High boiling below zero degree celsius

(c) Solid water contrast when heated

(d) Solid water is less dense than liquid water

 

6. When an external constraint such as change in concentration, pressure is imposed on a chemical system in equilibrium, the equilibrium will shift to annul or neutralize the constraint. The above statement is called ______.

(a) Law of multiple proportion

(b) Le Chatelier’s principle

(c) Reversible reaction

(d) Equilibrium reaction

 

7. Coffee stains are removed by ______.

(a) turpentine

(b) ammonia

(c) borax in water

(d) petrol

 

8. Solid is to true solution as ______ is to colloids.

(a) dispersion medium

(b) dispersed phase

(c) crystalloids

(d) aeration

 

9. The following are examples of colloids except ______.

(a) smoke

(b) foam

(c) emulsion

(d) plants

 

10. Which of the following metals will react with cold water to produce hydrogen gas?

(a) Calcium

(b) Aluminum

(c) Copper

(d) Magnesium

 

11. A graph of solubility against temperature is called ______?

(a) Sigmoid curve

(b) Supernant curve

(c) Solubility curve

(d) Dispersion

 

12. The solubility of alcohol in water is due to ______?

(a) their covalent nature

(b) hydrogen bonding

(c) their low boiling point

(d) their low freezing point (e) Ionic character

 

13. The following methods are used to prepare hydrogen industrially except ______.

(a) from water gas

(b) from methane

(c) by electrolysis

(d) by electrochemical method

 

14. The following are aliphatic hydrocarbon except ______?

(a) alkane

(b) alkene

(c) alkyne

(d) benzene

 

15. Which of these is not an extract of petroleum?

(a) gasoline

(b) Kerosene

(c) Diesel

(d) Water

 

16. Which of these is not an aromatic compound?

(a) Benzene

(b) Phenol

(c) Toluene

(d) Methane

 

17. The gas use in weldering of iron is ______.

(a) H2

(b) O2

(c) C2H4

(d) C2H2

 

18. The oxidation state of hydrogen in hydride of nitrogen is ______?

(a) +1

(b) + 3

(c) – 3

(d) – 1

 

19. Sodium hydroxide reacts with water to produce ______.

(a) acidic solution

(b) liberate hydrogen gas

(c) form a salt

(d) liberate oxygen

 

20. Oxygen is obtained from liquid air by ______.

(a) fermentation

(b) fractional l distillation

(c) filtration

(d) sublimation

 

21. ______ turns blue litmus paper red.

22. The mixture of kerosene and water can be separated by ______.

23. What is a standard solution?

24. Mention 3 indicators.

25. ______ is used to measure the volume of an acid.

(a) Pipette

(b) Burette

(c) Beaker

 

26. How can you identify a substance to be water ?

27. ______ give a lilac color when heated.

(a) Ca

(b) K

(c) Na

 

28. Mention two laboratory accident and how it can be prevented.

29. Name three apparatus used during filtration process.

30. Identify the apparatus you would use to carry out the following in the laboratory.

(a) Separating two immiscible liquids

(b) Condensing steam to liquid

 

THEORY –  ANSWER ANY FOUR (4) QUESTIONS ONLY.

QUESTION 1

A. Describe how river water is treated and rendered suitable for human consumption.

B. Some samples of hard water can be softened easily by boiling while others required chemical treatment for softening. Justify this statement. Give three chemical methods for removing the hardness of water. Write the respective equations.

 

QUESTION 2

A. Water was added to 50g of sodium chloride to produce 100cm3 of a saturated solution at 25oC. If the solubility of the salt at the temperature is 7mol/dm3. Calculate the number of moles of undissolved salt.

B. What is saturated, unsaturated and supersaturated solution?

C. Define the term solubility of a solution.

 

QUESTION 3

A. Ycm3 of hydrogen chloride gas HCl at S.T.P were passed into 6ocm3 of 0.1mol/dm3 sodium trioxocarbonate(IV), Na2CO3 solution. The excess trioxocarbonate(IV) was neutralized by 20cm3 of 0.05mol/dm3 tetraoxosulphate(VI), H2SO4. Calculate A. the mass of excess sodium trioxocarbonate(IV) in g/dm3. B. The value of Y. (Molar volume of a gas at S.T.P = 22.43, Na2CO3=106g)

B. What is standard solution?

 

QUESTION 4

A. What is hydrocarbon?

B. Give the molecular formula and structural formula of the first five members of the alkane family.

 

QUESTION 5

A is a solution of an acid, hydrogen chloride. B is a solution of sodiumtrioxocarbonate(iv) containing 0.05mol/dm³ solution. A was titrated against 25cm³ of solution B, using methyl orange as an indicator during the process, the average volume of the acid used is 24.40 cm³.

Given that H = 1, Cl = 35.5, Na = 23, C = 12, O = 16

The equation of the reaction is 2HCl + Na2CO3 ⇨ 2NaCl + H2O + CO2.

A. Calculate the concentration of the acid in mol/dm³

B. Calculate the concentration of the acid in g/dm³