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WAEC WASSCE Chemistry 2015 past questions and answers

This 2015 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 2015 set with instant marking.

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Sample WAEC WASSCE Chemistry 2015 questions

1. In the Contact process, which catalyst is used to convert sulfur dioxide to sulfur trioxide?
  1. Vanadium(V) oxide
  2. Nickel
  3. Iron
  4. Manganese(IV) oxide

Answer: A. Vanadium(V) oxide

Vanadium(V) oxide catalyses the oxidation of sulfur dioxide to sulfur trioxide in the Contact process.

2. Which substance is most suitable for scrubbing sulfur dioxide from acidic industrial flue gases?
  1. Sodium chloride solution
  2. Calcium hydroxide slurry
  3. Ethanol
  4. Dilute nitric acid

Answer: B. Calcium hydroxide slurry

Calcium hydroxide neutralizes sulfur dioxide to form calcium sulfite, reducing this acidic pollutant.

3. Which process is a major source of nitrogen oxides in urban air?
  1. Evaporation of seawater
  2. Photosynthesis in trees
  3. Combustion of fuel in hot vehicle engines
  4. Rusting of iron

Answer: C. Combustion of fuel in hot vehicle engines

At high engine temperatures, nitrogen and oxygen from air react to form nitrogen oxides.

4. A river sample has a very high biochemical oxygen demand (BOD); what does this most strongly indicate?
  1. The water contains no microorganisms
  2. The water is unusually rich in dissolved oxygen
  3. The water contains only dissolved mineral salts
  4. The water contains much biodegradable organic matter that can deplete oxygen

Answer: D. The water contains much biodegradable organic matter that can deplete oxygen

A high BOD means microorganisms are likely to use much dissolved oxygen while decomposing organic matter.

5. Members of a homologous series differ successively by which group of atoms?
  1. CH2
  2. CH3
  3. OH
  4. COOH

Answer: A. CH2

Successive members of a homologous series differ in molecular formula by one CH2 unit.

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