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 371: 1.00g of mixture of calcium carbonate and calcium oxide liberated 0.33g of carbon dioxide on strong heating. The percentage of calcium oxide in the mixture is? (Ca = 40, C = 12, O = 16) Options:
  A) 5
  B) 15
  C) 25
  D) 35
  E) 50
  Show Answer
  The correct answer is C .
• Question 372: 3Cl₂ + 2NH₃ $\to$ N₂ + 6HCl. In the above reaction, ammonia acts as Options:
  A) a reducing agent
  B) an oxidizing agent
  C) an acid
  D) a catalyst
  E) a dry agent
  Show Answer
  The correct answer is A .
• Question 373: The stability of the noble gases is due to the fact that they Options:
  A) have no electron in their outermost shells
  B) have duplet or octet electron configurations
  C) belong to group zero of the periodic table
  D) are volatile in nature
  Show Answer
  The correct answer is B .
• Question 374: When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as Options:
  A) disintegration
  B) polymerization
  C) cracking
  D) degradation
  E) distillation
  Show Answer
  The correct answer is C .
• Question 375:

  What volume of oxygen measured at s.t.p would be liberated on electrolysis by 9650 coulombs of electricity?

  (Molar volume of gas = 22.4 dm³, F = 96,500 C mol^-)

  Options:
  A) 22.4 dm³
  B) 11.2 dm³
  C) 1.12 dm³
  D) 0.560 dm³
  Show Answer
  The correct answer is D .
• Question 376:

  The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is

  Options:
  A) Na${}_2$SO${}_4$
  B) Na${}_2$SO${}_3$
  C) Na${}_2$S
  D) Na${}_2$CO${}_3$
  Show Answer
  The correct answer is B .
• Question 377:

  Which of the following is a unique property of water compared to other liquids?

  Options:
  A) It is a poor solvent
  B) It does not evaporate
  C) It expands when freezing
  D) It has a low heat capacity
  Show Answer
  The correct answer is C .
• Question 378:

  CH_4(g) + Cl_2(g) → CH₃ Cl_(s) + HCl_(g)

  The major factor that influence the rate of the reaction above is

  Options:
  A) catalyst
  B) temperature
  C) concentration
  D) light
  Show Answer
  The correct answer is D .
• Question 379: 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 380: Which of the following is an acidic salt? Options:
  A) NaHSO₄
  B) Na₂SO₄
  C) CH₃CO₂Na
  D) Na₂S
  Show Answer
  The correct answer is A .