2A6 Chapter 11 Practice Questions

1. 1. Match the following to the correct type of reaction that is occuring.

• thermal decomposition

• charcoal burning

• oxidation

• adding sulfuric acid to sodium hydroxide

• Combustion

• iron rods rusting

• neutralisation

• heating sugar strongly

2. 2. In a school laboratory, a student added hydrochloric acid to potassium hydroxide. This resulted in the formation of two products, potassium chloride and water.

What is the type the chemical reaction that occurred?

• combustion

• thermal decomposition

• oxidation

• neutralisation

2(b) Explain why the reaction in 2(a) in a chemical change.

ANS: It is because the reactants reacted to form ....................... substances,

potassium chloride and water.

1(c) Write a word equation to represent the reaction in Question 2(a).

hydrochloric acid + ​ ​ (a)   -> ​ (b)   + water

• potassium hydroxide
• potassium chloride

2(d) In order to obtain dry potassium chloride, evaporation was carried out on the mixture of potassium chloride and water. Explain whether evaporation is a physical or chemical change.

ANS: It is ​a ​ (a)   change. When evaporation was carried out, the water turned into​ (b)   , and no​ (c)   substances were​ (d)  

• physical
• water vapour
• new
• formed.

3(a) Avani inferred that solution Y is alkaline and solutions X and Z are acidic. Siti inferred that solution Y is alkaline and solutions X and Z can be acidic or neutral. Whom do you agree with? Explain your answer.

ANS: Siti. Red litmus paper will remain ​ (a)   in an acidic solution and also a neutral solution. Hence X and Z could either be ​ (b)   or neutral.

• acidic
• red

4(b) Suggest one way to determine whether solutions X and Z are acidic. Explain your answer.

ANS: Use blue litmus to test X and Z. If the blue litmus remains blue, the solution is ​ (a)   . If the blue litmus turns ​ (b)   , the solution is acidic.

• neutral
• red

4(a) Describe how the pH value changed when dilute sulfuric acid was added to the alkali in the beaker until the Universal Indicator turned green.

ANS: At first, the pH was above ​ (a)   .

When dilute sulfuric acid was added, the pH started to ​ (b)   ,

until the pH reached 7 and the Universal Indicator turned ​ (c)   .

• decrease
• green
• 7

4(b) One of the products formed during the reaction was potassium sulfate. What other product was formed?

• water

• potassium sulfate

• potassium hydroxide

• sulfuric acid

4(c) Write the word equation to represent the reaction that took place.

potassium hydroxide +​ (a)   -> ​ (b)   + water

• sulfuric acid
• potassium sulfate