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 811:

  An element Z contains 80% of ${}_8^{16}$Z and 20% of ${}_8^{18}$Z. Its relative atomic mass is

  Options:
  A) 16.2
  B) 17.6
  C) 16.0
  D) 16.4
  Show Answer
  The correct answer is D .
• Question 812: The compounds CH₃CH₂CHO and CH₃COCH₃ can be distinguished from each other using Options:
  A) Dilute ammonia
  B) Benedict's solution
  C) Tollen's reagent
  D) Sodium hydroxide solution
  Show Answer
  The correct answer is C .
• Question 813:

  A given volume of methane diffuses in 20s. How long will it take the same volume of sulphur (IV) oxide to diffuse under the same conditions?

  [C = 12, H = 1, S = 32, O = 16].

  Options:
  A) 5s
  B) 20s
  C) 40s
  D) 60s
  Show Answer
  The correct answer is C .
• Question 814: What will happen if an aluminium spoon is used to stir a solution of iron (II) trioxonitrates (V)? Options:
  A) The spoon will be oxidized while the iron (II) ions will be reduced to the metal
  B) The spoon will increase in size
  C) The spoon will be reduced while the iron (II) ions will be oxidized
  D) The spoon will be reduced
  Show Answer
  The correct answer is A .
• Question 815:

  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 816: A small quantity of solid ammonium chloride (NH₄Cl) was heated gently in a test tube, the solid gradually disappears to produce two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone Options:
  A) distillation
  B) sublimation
  C) precipitation
  D) evaporation
  E) decomposition
  Show Answer
  The correct answer is B .
• Question 817: An element, Z froms an anion whose formula is [Z(CN)₆]^y. If Z has an oxidation number of +2, what is the value of y? Options:
  A) - 2
  B) - 3
  C) - 4
  D) - 5
  Show Answer
  The correct answer is C .
• Question 818: The intermediate product formed when ethanol is progressively oxidized to ethanoic acid with potassium heptaoxodichromate (IV) is Options:
  A) butanal
  B) ethanal
  C) methanal
  D) propanal
  Show Answer
  The correct answer is B .
• Question 819: Which of the following results in the fall of acid rain Options:
  A) oxide of lead
  B) particulate matter
  C) oxides of carbon
  D) gaseous hydrocarbon
  Show Answer
  The correct answer is C .
• Question 820: Alkaline hydrolysis of naturally occurring fats and oils yields Options:
  A) fats and acids
  B) soaps and glycerol
  C) margarine and butter
  D) esters
  E) detergents
  Show Answer
  The correct answer is B .