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 431: The nitrogen obtained from air has a density higher than the one from nitrogen-containing compounds because the one from air is contaminated with Options:
  A) water vapour
  B) oxgyen
  C) rare gases
  D) carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 432: Which of the following will change when a catalyst is added to a chemical reaction? Options:
  A) The activation energy
  B) The potential energy of the reactants
  C) The heat of the reaction
  D) the potential energy of the product
  Show Answer
  The correct answer is A .
• Question 433:

  The velocity, V of a gas is related to its mass, M by (k = proportionality constant)

  Options:
  A) V = $\frac{k}{M}$
  B) V = $\frac{k}{M^{\frac{1}{2}}}$
  C) V = $k{M}^2$
  D) V = $(\frac{k}{M}{)}^{\frac{1}{2}}$
  Show Answer
  The correct answer is B .
• Question 434:

  If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be

  Options:
  A) 2.2M
  B) 1.1M
  C) 0.22M
  D) 0.11M
  Show Answer
  The correct answer is C .
• Question 435: The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is Options:
  A) Phosphorus-32
  B) Cobalt-60
  C) Carbon-14
  D) Iodine-131
  Show Answer
  The correct answer is B .
• Question 436:

  

  The following graph demonstrates the rate of reaction between calcium carbonate (marble)and dilute hydrochloric acid. The graph shows that the rate of reaction is initially greatest when

  Options:
  A) the initial slope of the curve is steepest and this occur when small pieces of marble are used and is due to a small surface area of reactant
  B) the occur when large pieces of marble are used and is due to a small surface area of reactant
  C) the initial slope of the curve is steepest and this occurs when small pieces of marble are used and is due to a large surface area of reactant
  D) the initial slope of the curve is steepest and this occur when large surface area of reactant
  E) the initial slope of the curve is least steep and this occur when small pieces of marble are used and is due to the increased surface area of the reactant
  Show Answer
  The correct answer is C .
• Question 437:

  What is the mass percentage of carbon (C) in methane (CH4)? (The molar mass of carbon is approximately 12 g/mol.)

  Options:
  A) 25%
  B) 12%
  C) 75%
  D) 50%
  Show Answer
  The correct answer is C .
• Question 438:

  Beryllium and Aluminium have similar properties because they

  Options:
  A) are both metals
  B) belong to the same group
  C) belong to the same period
  D) are positioned diagonally to each other
  Show Answer
  The correct answer is D .
• Question 439:

  What is the percentage by mass of oxygen in Al₂(SO₄)₃. 2H₂O?

  [Al = 27, S = 32, H = 1, O = 16]

  Options:
  A) 14.29%
  B) 25.39%
  C) 50.79%
  D) 59.25%
  Show Answer
  The correct answer is D .
• Question 440:

  

  The oxidation of

  Options:
  A) 2-butanone
  B) 2-butanal
  C) butane
  D) butanoic acid
  E) 3-butanal
  Show Answer
  The correct answer is A .