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 21: The leachate of a certain plant ash is used in local soap making because it contains Options:
  A) sodium chloride and potassium hydroxide
  B) sodium hydroxide
  C) potassium hydroxide
  D) soluble carbonates and hydrogen carbonates
  Show Answer
  The correct answer is B .
• Question 22: The fuming of kettles is caused by the presence in the water of Options:
  A) Calcium tetraoxosulphate (VI)
  B) Calcium hydrogentrioxocarbonate (IV)
  C) Calcium hydroxide
  D) Calcium trioxocarbonate (IV)
  Show Answer
  The correct answer is B .
• Question 23:

  The atomic weight of nitrogen is?

  Options:
  A) 10
  B) 12
  C) 14
  D) 16
  Show Answer
  The correct answer is C .
• Question 24: Which one of the following metals is not normally extracted by chemical reduction because of its position in the electrochemical series? Options:
  A) Copper
  B) Iron
  C) Lead
  D) Potassium
  E) Zinc
  Show Answer
  The correct answer is D .
• Question 25:

  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 26: When iron is exposed to moist air, it gradually rusts. This is due to the formation of Options:
  A) hydrate iron (III) oxide
  B) anhydrous iron (III) oxide
  C) anhydrous iron (II) oxide
  D) hydrate iron (II) oxide
  Show Answer
  The correct answer is A .
• Question 27: According to the kinetic theory an absence in temperature causes the kinetic energy of particles to Options:
  A) decrease
  B) increase
  C) remain constant
  D) be zero
  Show Answer
  The correct answer is D .
• Question 28: In which of the following reactions has the oxidation number of nitrogen increased? Options:
  A) 2NO_(g) + Br_2(l) → 2NOBr_(l)
  B) 2NO_(g) + O_2(g) → 2NO_2(g)
  C) FeSO_4(aq) + NO_(g) → Fe(NO)SO_4(s)
  D) 2NO(g) + Cl_2(g) → 2NOCl(l)
  Show Answer
  The correct answer is B .
• Question 29:

  Wrought iron is obtained by heating cast iron in a furnace with?

  Options:
  A) magnetite
  B) haematite
  C) carbon(ii)oxide
  D) calcium trioxosilicate(iv)
  Show Answer
  The correct answer is B .
• Question 30:

  Calculate the pH of 0.05 moldm${}^{-3}$ H${}_2$SO${}_4$

  Options:
  A) 1.30
  B) 1.12
  C) 1.00
  D) 0.30
  Show Answer
  The correct answer is A .