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 2161:

  What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?

  Options:
  A) 24,125 C
  B) 48,250 C
  C) 72,375 C
  D) 96,500 C
  Show Answer
  The correct answer is B .
• Question 2162: The product formed at the the cathode during the electrolysis of sodium chloride solution with carbon electrodes is? Options:
  A) sodium
  B) chlorine
  C) hydrogen
  D) sodium hydroxide
  E) oxygen
  Show Answer
  The correct answer is C .
• Question 2163: When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains? Options:
  A) NaOH
  B) KOH
  C) Mg(OH)₂
  D) Zn(OH)₂
  E) Ca(OH)₂
  Show Answer
  The correct answer is E .
• Question 2164: If an equilibrium reaction has ∆H < O, the reaction will proceed favorably in the forward reaction at? Options:
  A) low temperatures
  B) high temperatures
  C) all temperatures
  D) all pressures
  Show Answer
  The correct answer is A .
• Question 2165: How many isomers does pentane have? Options:
  A) 6
  B) 5
  C) 4
  D) 3
  Show Answer
  The correct answer is D .
• Question 2166: A man suspected of being drunk is made to pass his breath into acidified potassium dichlormate solution. If his breath carries a significant level of ethanol, the final colour of the solution is? Options:
  A) pink
  B) purple
  C) orange
  D) blue-black
  E) green
  Show Answer
  The correct answer is E .
• Question 2167: Ca(OH)_2(s) + 2NH₄Cl_(g) → CaCl_2(s) + 2H₂O_2(l) + X. In the reaction above X is Options:
  A) NO₂
  B) NH₃
  C) N₂O
  D) NO₂
  Show Answer
  The correct answer is B .
• Question 2168:

  Cr₂O$\frac{2-}{7}$ (aq) + H₂O(1)⇌ 2CrO $\frac{2-}{4}$ (aq) + 2H ⁺ (aq)

  What happens to the reaction above when the hydrogen ion concentration is increased?

  Options:
  A) more of the products will be formed
  B) the reaction will not proceed
  C) the equilibrium position will shift to the right
  D) the equilibrium position will shift to the left.
  Show Answer
  The correct answer is D .
• Question 2169:

  Which of the following is an example of a chemical change?

  Options:
  A) dissolution of salt in water
  B) rusting of iron
  C) melting of ice
  D) separating a mixture by distillation
  Show Answer
  The correct answer is B .
• Question 2170: Air boiled out of water as steam is richer in Options:
  A) nitrogen and oxygen
  B) carbon (IV) oxide and oxygen
  C) noble gases and carbon (IV) oxide
  D) oxygen and noble gases
  Show Answer
  The correct answer is B .