Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 1971: How will a metal X, which reacts explosively with air and with dilute acids be best extracted from its ores? Options:
  A) Electrolysis of solution of its salts
  B) Decomposition of its oxides
  C) Displacement from solution by an alkali metal
  D) Electroiysis of fused salt
  Show Answer
  The correct answer is D .
• Question 1972: Calculate the volume of carbon (IV)oxide measured at s.t.p, produced when 1 kg of potassium hydrogen trioxocarbonate (IV) is totally decomposed by heat?(G.M.V. at s.t.p 22.4 dm³, K = 39, O = 16, C = 12, H = 1) Options:
  A) 28 dm³
  B) 56 dm³
  C) 112 dm³
  D) 196 dm³
  Show Answer
  The correct answer is C .
• Question 1973: The major component of the slag from the production of iron is? Options:
  A) an alloy of calcium and iron
  B) coke
  C) impure iron
  D) calcium trioxosilicate (IV)
  Show Answer
  The correct answer is B .
• Question 1974: Which of the following roles does sodium chloride play in soap preparation? It Options:
  A) reacts with glycerol
  B) purifies the soap
  C) accelerates the decomposition of the fat or oil
  D) separates the soap from the glycerol
  E) converts the fatty acid to its sodium salt
  Show Answer
  The correct answer is D .
• Question 1975:

  The following compounds are given with their corresponding boiling points.

  Compound Boiling Point

  i.................................14°C

  ii................................24°C

  iii................................0°C

  iv................................120°C

  V.................................-2°C

  From the above information, indicate which of the following is correct?

  Options:
  A) All the compounds are gaseous at 20 °C
  B) One of the compounds is gaseous at 20 °C
  C) Two of the compounds are gaseous at 20 °C
  D) Three of the compounds are gaseous at 20 °C
  E) None of the compounds is gaseous at 20 °C
  Show Answer
  The correct answer is D .
• Question 1976: In which of the following reactions can the oxidation number of the nitrogen be said to have increased? Options:
  A) 2NO_(g) + O_2(g) → 2NO_2(g)
  B) NO_(g) + Cl_2(g) → NOCl_2(l)
  C) FeSO_4(aq) + NO_(g) → Fe(NO)SO_4(s)
  D) NO_(g) + Br_2(l) → NOBr_2(l)
  Show Answer
  The correct answer is A .
• Question 1977: The chemical reaction which takes place at the anode (positive electrode) in electrolysis is? Options:
  A) oxidation
  B) hydrolysis
  C) dissociation
  D) reduction
  E) disproportionation
  Show Answer
  The correct answer is A .
• Question 1978: An undesirable paraffin in the petroleum industry which is particularly prone to knocking is? Options:
  A) iso-octane
  B) n-heptane
  C) iso-heptane
  D) n-octane
  Show Answer
  The correct answer is B .
• Question 1979:

  Which of the following is used to power steam engines?

  Options:
  A) lubricating oil
  B) coal
  C) bitumen
  D) diesel oil
  Show Answer
  The correct answer is B .
• Question 1980: Hydrogen is not liberated when trioxonitrate(v)acid reacts with zinc because Options:
  A) zinx is not rendered passive by acid
  B) hydrogen produced is oxidized to water
  C) oxides of nitrogen are produced
  D) all nitrates are soluble in water
  E) trioxonitrate(v)acid is a strong acid
  Show Answer
  The correct answer is E .