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 51: An element with atomic number twelve is likely to be Options:
  A) electrovalent with a velocity of 1
  B) electrovalent with a valency of 2
  C) covalent with a valency of 2
  D) covalent with valency of 4
  Show Answer
  The correct answer is B .
• Question 52: In the extraction of iron, which of the following reactions does NOT take place in the blast furnace? Options:
  A) CO₂ + C → 2CO
  B) 2Fe₂O₃ + 3C → 4Fe + 3CO₂
  C) Fe₂O₃ + 3C → 2Fe + 3CO₂
  D) CaCO₃ → CaO + CO₂
  E) CaO + SiO₂ → CaSiO₃
  Show Answer
  The correct answer is B .
• Question 53:

  CU₂S_(s) + O_2(g) → 2CU_(s) + SO_2(g)

  What is the change in the oxidation number of copper in the reaction above?

  Options:
  A) +1 to 0
  B) 0 to +2
  C) +2 to +1
  D) 0 to +1
  Show Answer
  The correct answer is A .
• Question 54:

  When anhydrous cobalt chloride paper is exposed to water, what color change is observed?

  Options:
  A) From pink to blue
  B) From white to blue
  C) From blue to white
  D) From blue to pink
  Show Answer
  The correct answer is D .
• Question 55:

  (I). 3CuO(s) + 2NH3(g) -----> 3Cu(s) + 3H2O(l) + N2(g) 

  (II). 2NH3(g) + 3Cl2(g) -----> 6HCl(g) + N2(g) 

  (III). 4NH3(g) + 3O2(g) -----> 6H2O(l) + N2(g) 

  The reactions represented by the equations above demonstrate the

  Options:
  A) basic properties of ammonia
  B) acidic properties of ammonia
  C) reducing properties of ammonia
  D) oxidizing properties of ammonia
  Show Answer
  The correct answer is C .
• Question 56: An emulsion paint consists of ? Options:
  A) gas or liquid particles dispersed in liguid
  B) liquid particles dispersed in liquid
  C) solid particles dispersed in liquid
  D) solid particles dispersed in solid
  Show Answer
  The correct answer is B .
• Question 57:

  

  In the above experiment X is

  Options:
  A) pure nitrogen
  B) a mixture of nitrogen and oxygen
  C) a mixture of nitrogen and carbondioxide
  D) a mixture of oxygen and inert gases
  E) a mixture of nitrogen and inert gases
  Show Answer
  The correct answer is E .
• Question 58: The gas responsible for most of the fatal explosions in coal mines is Options:
  A) butane
  B) ethene
  C) ethane
  D) methane
  Show Answer
  The correct answer is D .
• Question 59: Copper (II) tetraoxosulphate (IV) is widely used as a? Options:
  A) fertilizer
  B) fungicide
  C) disinfectant
  D) purifier
  Show Answer
  The correct answer is B .
• Question 60:

  3Cu_(s) + 8HNO_3(aq) 3Cu(NO₃)_2(aq) + 4H₂O_(l) + 2NO_(g)

  In the equation above, copper is

  Options:
  A) an electron acceptor
  B) a base
  C) an oxidizing agent
  D) a reducing agent
  Show Answer
  The correct answer is D .