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 1221:

  

  In the electrolysis of aqueous solution of K₂SO ₄ in the above cell, which species migrate to the anode?

  Options:
  A) SO^2-OH ^-
  B) K ⁺ and SO ₄^2-
  C) OH and HO
  D) H₃O ⁺ and K
  Show Answer
  The correct answer is A .
• Question 1222: Suitable reagents for the laboratory preparation nitrogen are? Options:
  A) sodium dioxonitrate (III) and ammonium chloride
  B) sodium dioxonitrate (V) and ammonium chloride
  C) sodium chloride and ammonium chloride
  D) sodium chloride and ammonium diozonitrate (III)
  Show Answer
  The correct answer is A .
• Question 1223: The gas that can best be collected by downward displacement of air is Options:
  A) Chlorine
  B) Sulphur (IV) oxide
  C) Ammonia
  D) Carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 1224: The flame used by welders in cutting metals is Options:
  A) butane gas flame
  B) acetylene flame
  C) kerosene flame
  D) oxy-acetylene flame
  E) oxygen flame
  Show Answer
  The correct answer is D .
• Question 1225: Alloys are best prepared by? Options:
  A) high temperature weilding of the metals
  B) electrolysis using the major metallic component as cathode
  C) reducing a mixture of the oxies of the elements
  D) cooling a molten mixture of the necessary elements
  Show Answer
  The correct answer is D .
• Question 1226: The structural component that makes detergent dissolve more quickly in water than soap is Options:
  A) -SO₃- Na⁺
  B) -COO-Na^-
  C) -SO₄- Na⁺
  D) -COO-K⁺
  Show Answer
  The correct answer is A .
• Question 1227:

  A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.

  [H = 1, C = 12, O = 16]

  Options:
  A) C${}_3$H${}_6$O${}_3$
  B) C${}_6$H${}_6$O${}_3$
  C) C${}_6$H${}_{12}$O${}_6$
  D) CH${}_2$O
  Show Answer
  The correct answer is C .
• Question 1228: In the production of soap, concentrated sodium chloride solution is added to Options:
  A) increase the solubility of soap
  B) decrease the solubility of the soap
  C) saponify the soap
  D) emulsify the soap
  Show Answer
  The correct answer is B .
• Question 1229:

  The presence of ammonia gas in a desiccator can exclusively be removed by

  Options:
  A) phosphorus (V) oxide
  B) fused calcium chloride
  C) calcium chloride
  D) concentrated tetraoxosulphate (VI) acid
  Show Answer
  The correct answer is D .
• Question 1230: In the process of silver-plating a metal M, the metal M is the? Options:
  A) anode and a driect current is used
  B) cathode and an alternating current is used
  C) anode and an alternating current is used
  D) cathode and a direct current is used
  Show Answer
  The correct answer is B .