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WAEC WASSCE Chemistry 2013 past questions and answers

This 2013 WAEC WASSCE Chemistry set has 40 practice questions. Try these 5 free sample questions, tap a question to reveal the answer and explanation. Then practise the whole 2013 set with instant marking.

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Sample WAEC WASSCE Chemistry 2013 questions

1. When ethane reacts with bromine in ultraviolet light, which type of reaction produces bromoethane?
  1. Substitution
  2. Addition
  3. Neutralization
  4. Polymerization

Answer: A. Substitution

A bromine atom replaces a hydrogen atom in ethane, so the reaction is substitution.

2. Which conditions are suitable for preparing ethyl ethanoate from ethanol and ethanoic acid?
  1. Aqueous sodium hydroxide at room temperature
  2. Dilute hydrochloric acid without heating
  3. Concentrated sulfuric acid and heating
  4. Nickel catalyst and high pressure

Answer: C. Concentrated sulfuric acid and heating

Heating ethanol with ethanoic acid in the presence of concentrated sulfuric acid promotes esterification.

3. What is the repeating unit in the addition polymer formed from propene, CH2=CHCH3?
  1. -CH2-CH2-
  2. -CH2-CH(CH3)-
  3. -CH(CH3)-CH(CH3)-
  4. -CH2-CH2-CH2-

Answer: B. -CH2-CH(CH3)-

The double bond opens and the propene units join while retaining one CH3 group on every second carbon.

4. Why can the components of crude oil be separated by fractional distillation?
  1. They have different densities only
  2. They react at different rates with oxygen
  3. They are all immiscible liquids
  4. They have different boiling-point ranges

Answer: D. They have different boiling-point ranges

Crude-oil fractions condense at different levels because their hydrocarbons have different boiling-point ranges.

5. Why does soap form scum when used in hard water?
  1. Soap reacts with calcium or magnesium ions to form insoluble salts
  2. Soap decomposes completely into carbon dioxide
  3. Hard water changes soap into an acid
  4. Soap evaporates before it can dissolve

Answer: A. Soap reacts with calcium or magnesium ions to form insoluble salts

Calcium and magnesium ions in hard water form insoluble salts with soap anions, producing scum.

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