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 1:

  A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?

  Options:
  A) sulphur (lV) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
  Show Answer
  The correct answer is A .
• Question 2: The hydroxyl ion concentrated, (OH^-), in a solution of sodium hydroxide of pH 10.0 is? Options:
  A) 10^-10 mol dm^-3
  B) 10^-6 mol dm^-3
  C) 10^-4 mol dm^-3
  D) 10^-2 mol dm^-3
  Show Answer
  The correct answer is C .
• Question 3:

  MnO^-_4(aq) + Y + 5Fe²⁺_(aq) → Mn²⁺_(aq) + 5Fe²⁺_(aq) + 4H₂O^(l)

  In the equation above, Y is

  Options:
  A) 5H⁺_(aq)
  B) 4H⁺_(aq)
  C) 10H⁺_(aq)
  D) 8H⁺_(aq)
  Show Answer
  The correct answer is D .
• Question 4:

  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 5: The gaseous pollutant sulphur (IV)oxide is most likely to be detected in fairly reasonable quantities in the area around a plant for the Options:
  A) extraction of aluminium from bauxite
  B) production of margarine
  C) smelting of copper
  D) production of chlorine from brine
  Show Answer
  The correct answer is C .
• Question 6: Dissolving some pellets of NaOH in water would result in Options:
  A) a decrease in the free energy of the solution
  B) a decrease in the entropy of the solution
  C) a lowering of the temperature of te solution
  D) an increase in the entropy of the solution
  Show Answer
  The correct answer is D .
• Question 7: The noble gas, argon,is used for Options:
  A) electric arc welding
  B) welding brass
  C) underwater welding
  D) steel welding
  Show Answer
  The correct answer is A .
• Question 8: Which of the following is a property of ionic chlorides? Options:
  A) They can be decomposed by heat
  B) They react with aqueous AgNO₃ to give a white precipiate which is soluble in excess ammonia
  C) They explode when in contact with dry ammonia
  D) They react with concentrated tetraoxosulphate (IV) acid to give white fumes of chlorine gas
  Show Answer
  The correct answer is B .
• Question 9: The chromatography separation of ink is based on the ability of the components to Options:
  A) React with solvent
  B) React with each other
  C) Dissolve in each other in the column
  D) Move at different speeds in the column
  Show Answer
  The correct answer is D .
• Question 10: When copper (ii) sulphate solution is treated with excess ammonium hydroxide, a precipitate is first formed, and then this dissolves to give a deep blue solution. This deep blue solution is a Options:
  A) Cu(OH)₂
  B) CuSo₄.5H₂O
  C) (NH₄)₂SO₄
  D) Cu(NH₃)₄(OH)₂
  E) CuSO₄.(NH₄)₂SO₄.2H₂O
  Show Answer
  The correct answer is E .