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 131:

  2Na ₂ O _2(s) + 2H ₂ O ₂₍₁₎ → 4 NaOH_(s) +O_2(s)

  The substance that is oxidized in the reaction above is

  Options:
  A) 2NaO_2(s)
  B) NaOH(aq)
  C) H₂O₍₁₎
  D) O_2(g)
  Show Answer
  The correct answer is A .
• Question 132: A particle that contains 9 protons, 10 neutrons and 10 electrons is a Options:
  A) negative ion
  B) positive ion
  C) neutral atom of non-metal
  D) neutral atom of a metal
  Show Answer
  The correct answer is A .
• Question 133: The type of reaction that is peculiar to benzene is Options:
  A) addition
  B) hydrolysis
  C) polymerization
  D) substitution
  Show Answer
  The correct answer is D .
• Question 134: A silicon -containing ore has 92% ²⁸Si, 5% ²⁹Si and 3% ³⁰Si. Calculate the relative atomic mass of the silicon. Options:
  A) 14.00
  B) 29.00
  C) 28.11
  D) 28.00
  Show Answer
  The correct answer is C .
• Question 135: The ion that will give a white precipitate with aqueous NaOH and soluble in excess of the base is Options:
  A) Ca²⁺
  B) Mg²⁺
  C) Zn²⁺
  D) Cu²⁺
  Show Answer
  The correct answer is C .
• Question 136:

  I. H = 1s¹ II. N = 1s² 2s² p³ III. O = 1s² 2s² p⁴ IV. Zn = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰

  From the above, which of the following pairs is like to be paramagnetic?

  Options:
  A) I and II
  B) I and III
  C) I and IV
  D) III and IV
  Show Answer
  The correct answer is A .
• Question 137:

  In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:

  Anode Cathode

  Options:
  A) Sulphur hydrogen
  B) Hydrogen oxygen
  C) Oxygen Hydrogen
  D) Hydrogen sulphate ions
  E) Sulphur oxygen
  Show Answer
  The correct answer is C .
• Question 138: 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 139: $PC{l}_{5(g)}\to PC{l}_{3(g)}+C{l}_{2(g)}$
  In the reaction above, an increase in pressure will Options:
  A) decelerate the reaction
  B) Increase the yield of $PC{l}_3$
  C) increase the yield of $PC{l}_5$
  D) accelerate the reaction
  Show Answer
  The correct answer is C .
• Question 140: Which of the following hydrocarbons is mainly used as fuel? Options:
  A) Methylene
  B) Ethylene
  C) Methane
  D) Ethyne
  Show Answer
  The correct answer is C .