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 91:

  If 30cm³ of oxygen diffuses through a porous pot in 7 seconds, how long will it take 60cm³ of chlorine to diffuse through the same pot, if the vapour densities of oxygen and chlorine are 16 and 36 respectively?

  Options:
  A) 9.3 sec
  B) 14 sec
  C) 21 sec
  D) 28 sec
  E) 30.3 sec
  Show Answer
  The correct answer is C .
• Question 92: Which of the following equilibria is unaffected by a pressure change? Options:
  A) 2NaCI(s) ↔ 2Na _(I) + CI_2(g)
  B) H _2(g) + I_2(g) ↔ 2HI_(g)
  C) 2O_3(g) ↔ 3O_2(g)
  D) 2NO_2(g) ↔ N₂O_4(g)
  Show Answer
  The correct answer is B .
• Question 93: The product of the electrolysis of dilute sodium hydroxide using platinum electrodes are Options:
  A) Hydrogen and oxygen gases
  B) Water and hydrogen gas
  C) Water and sodium metal
  D) Sodium metal and oxygen gas
  Show Answer
  The correct answer is A .
• Question 94: When excess ethanol is heated to 145 ^oC in the presence of concentrated sulphuric acid, the product is Options:
  A) diethyl ether
  B) ethyne
  C) diethyl sulphate
  D) acetone
  E) ethanoic acid
  Show Answer
  The correct answer is A .
• Question 95: Hypochlorous acid is used as a bleach because Options:
  A) it is a strong acid
  B) it yields chlorine readily in pure water
  C) it is an oxidising agent
  D) it is a weak acid
  E) it is a reducing agent
  Show Answer
  The correct answer is C .
• Question 96: Which of the following represents an aromatic compound? Options:
  A) C₆H₅OH
  B) C₆H₁₂
  C) C₆H₉OH
  D) C₆H₈
  Show Answer
  The correct answer is A .
• Question 97: A polymerization reaction is one in which? Options:
  A) small molecules form giant molecules
  B) atoms form molecules
  C) giant molecules form small molecules
  D) molecules form volatile compounds
  E) a molecule rearranges itself
  Show Answer
  The correct answer is A .
• Question 98: The molecular formula of a common organic laboratory anaesthetic is Options:
  A) CHCl₃
  B) CHI₃
  C) CCl₄
  D) CHF₃
  Show Answer
  The correct answer is A .
• Question 99: In the experiment, which of the following observations would suggest that a solid sample is a mixture? The Options:
  A) solid can be ground to a fine powder
  B) density of the solid is 2.25gdm^-3
  C) solid begins to melt at 573k but is not completely melted until 648k
  D) solid absorbs moisture from the atmosphere and turns into liquid
  E) solid melts at 300k
  Show Answer
  The correct answer is C .
• Question 100: 0.07g of a hydride of carbon occupies 56.0cm³ at S.T.P. when vaporized and contains 14.29% by mass of hydrocarbon is(C = 12, H = 1) Options:
  A) CH₄
  B) C₂H₂
  C) C₂H₄
  D) C₂H₆
  E) C₃H₈
  Show Answer
  The correct answer is C .