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

Match the physical processes represented by arrows (i) - (v) in List A with the corresponding terms in List B by writing the letter of the correct response beside the item number in the answer booklet provided.

1. Physical process (1 mk)
2. Physical process (1 mk)
3. Physical process (1 mk)
4. Physical process (1 mk)
5. Physical process (1 mk)

Upgrade to see model answers.

(a) Giving an example for each, give four uses of matter in daily life. (b) Why are chemical symbols useful in Chemistry? Give three reasons.

1. Giving an example for each, give four uses of matter in daily life. (4 mk)
2. Giving an example for each, give four uses of matter in daily life. (4 mk)
3. Why are chemical symbols useful in Chemistry? Give three reasons. (3 mk)
4. Why are chemical symbols useful in Chemistry? Give three reasons. (3 mk)

Upgrade to see model answers.

(a) Give four laboratory apparatuses that are made up of porcelain/ceramic material. (b) Outline three steps of administering First Aid to a person having a bruise on his leg resulting from a fist/hand blow.

1. Give four laboratory apparatuses that are made up of porcelain/ceramic material. (4 mk)
2. Give four laboratory apparatuses that are made up of porcelain/ceramic material. (4 mk)
3. Outline three steps of administering First Aid to a person having a bruise on his leg resulting from a fist/hand blow. (3 mk)
4. Outline three steps of administering First Aid to a person having a bruise on his leg resulting from a fist/hand blow. (3 mk)

Upgrade to see model answers.

(a) What is the molarity of a solution containing 10% by mass of calcium hydroxide in 0.5 dm​3 ​ of solution? (b) 25 cm​3 of a molar solution of sodium hydroxide is diluted to 85 cm​3 ​. Calculate the concentration of the solution after dilution. (Give your answer in two decimal places).

1. What is the molarity of a solution containing 10% by mass of calcium hydroxide in 0.5 dm​3 ​ of solution? (4 mk)
2. What is the molarity of a solution containing 10% by mass of calcium hydroxide in 0.5 dm​3 ​ of solution? (3 mk)
3. 25 cm​3 of a molar solution of sodium hydroxide is diluted to 85 cm​3 ​. Calculate the concentration of the solution after dilution. (Give your answer in two decimal places). (3 mk)
4. 25 cm​3 of a molar solution of sodium hydroxide is diluted to 85 cm​3 ​. Calculate the concentration of the solution after dilution. (Give your answer in two decimal places). (4 mk)

Upgrade to see model answers.

(a) Briefly explain the basic steps you would follow in water treatment. (b) Outline how to test for the purity of water.

1. Briefly explain the basic steps you would follow in water treatment. (4 mk)
2. Briefly explain the basic steps you would follow in water treatment. (4 mk)
3. Outline how to test for the purity of water. (3 mk)
4. Outline how to test for the purity of water. (3 mk)

Upgrade to see model answers.

(a) Briefly explain five importance of balancing chemical equations. (b) Give a balanced chemical equation for the reaction between sodium carbonate and hydrochloric acid.

1. Briefly explain five importance of balancing chemical equations. (5 mk)
2. Briefly explain five importance of balancing chemical equations. (5 mk)
3. Give a balanced chemical equation for the reaction between sodium carbonate and hydrochloric acid. (2 mk)
4. Give a balanced chemical equation for the reaction between sodium carbonate and hydrochloric acid. (2 mk)

Upgrade to see model answers.

(a) Calculate the concentration in g/dm​3 of vinegar (CH​ COOH) if 25.0 cm​3 of 0.1 M sodium hydroxide reacts with 12.5 cm​3 ​ of vinegar. (b) By giving a reason, suggest the suitable indicator for the reaction in 8(a) above.

1. Calculate the concentration in g/dm​3 of vinegar (CH​ COOH) if 25.0 cm​3 of 0.1 M sodium hydroxide reacts with 12.5 cm​3 ​ of vinegar. (5 mk)
2. Calculate the concentration in g/dm​3 of vinegar (CH​ COOH) if 25.0 cm​3 of 0.1 M sodium hydroxide reacts with 12.5 cm​3 ​ of vinegar. (5 mk)
3. By giving a reason, suggest the suitable indicator for the reaction in 8(a) above. (2 mk)
4. By giving a reason, suggest the suitable indicator for the reaction in 8(a) above. (2 mk)

Upgrade to see model answers.

A Form Three student conducted an experiment to prepare a gas in the laboratory by decomposing a certain compound using electricity. She allowed a steady electric current to flow through the solution for 3 hours at s.t.p. If the volume the gas obtained was 4.12 dm​3 and the gas relighted a glowing splint; (a) name the gas that was produced. (b) calculate the electric current that was flowing in the solution.

1. name the gas that was produced. (2 mk)
2. name the gas that was produced. (2 mk)
3. calculate the electric current that was flowing in the solution. (5 mk)
4. calculate the electric current that was flowing in the solution. (5 mk)

Upgrade to see model answers.

(a) Draw diagrams to show the atomic structures of the elements with atomic number 1, 10, 16 and 19. (b) Element X has 20 electrons and a mass number of 40. Work out the number of each type of nucleons present.

1. Draw diagrams to show the atomic structures of the elements with atomic number 1, 10, 16 and 19. (7 mk)
2. Draw diagrams to show the atomic structures of the elements with atomic number 1, 10, 16 and 19. (4 mk)
3. Element X has 20 electrons and a mass number of 40. Work out the number of each type of nucleons present. (3 mk)

Upgrade to see model answers.

A certain compound having a relative molecular mass of 76 was found to contain 15.8% of carbon and 84.2% of sulphur. Based on this information: (a) determine the empirical formula and molecular formula of the compound. (b) give the IUPAC name of the compound.

1. determine the empirical formula and molecular formula of the compound. (5 mk)
2. give the IUPAC name of the compound. (2 mk)

Upgrade to see model answers.

(a) Ammonia gas is manufactured by reacting nitrogen gas with hydrogen gas in the presence of a catalyst. Write a balanced chemical equation for the reaction and explain the role played by the catalyst in this reaction. (b) The following figure shows the reaction path between sodium hydroxide and hydrochloric acid. Giving a reason, classify the reaction based on energetics and predict the effects of cooling the system while increasing pressure at the same time.

1. Ammonia gas is manufactured by reacting nitrogen gas with hydrogen gas in the presence of a catalyst. Write a balanced chemical equation for the reaction and explain the role played by the catalyst in this reaction. (3 mk)
2. The following figure shows the reaction path between sodium hydroxide and hydrochloric acid. Giving a reason, classify the reaction based on energetics and predict the effects of cooling the system while increasing pressure at the same time. (4 mk)

Upgrade to see model answers.

Carbon is one of the elements that have allotropes. Explain how the allotropes of carbon differ from each other.

1. Explain how the allotropes of carbon differ from each other. (15 mk)

Upgrade to see model answers.

Despite its corrosiveness, sulphuric acid is very important in industry. Explain the importance of sulphuric acid in industries by giving six points.

1. Explain the importance of sulphuric acid in industries by giving six points. (15 mk)

Upgrade to see model answers.