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 301: In the purification of town water supply, alum is used principally to? Options:
  A) kill bacteria
  B) control the pH of water
  C) improve the taste of the water
  D) coagulate small pasrticles of mud
  Show Answer
  The correct answer is D .
• Question 302:

  A mixture of iron and sulphur can be separated by dissolving the mixture in?

  Options:
  A) steam
  B) dilute hydrochloric acid
  C) dilute sodium hydroxide
  D) benzene
  Show Answer
  The correct answer is B .
• Question 303:

  The molar ratio of carbon to hydrogen of a volatile liquid compound is 1: 2. 0. 12 g of the liquid on evaporation at s.t.p. gave 32 cm³ of vapour. The molecular formula of the liquid is

  [G.M.V =22.4 dm ³, C = 12, H = 1]

  Options:
  A) C ₃ H ₆
  B) C ₄H ₈
  C) C ₅C ₁₀
  D) C ₆H ₁₂
  Show Answer
  The correct answer is D .
• Question 304: Reduction of alkanonoes with LialH₄ produces Options:
  A) primary alkanols
  B) secondary alkanols
  C) tertiary alkanols
  D) polyhydric alkanols
  Show Answer
  The correct answer is B .
• Question 305: A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is? Options:
  A) sulphur (ii) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
  Show Answer
  The correct answer is A .
• Question 306:

  How many pi ($\pi$) bonds are there in an alkene with six carbon atoms?

  Options:
  A) 4
  B) 6
  C) 5
  D) 3
  Show Answer
  The correct answer is D .
• Question 307: A piece of metal (M) is dissolved in nitric acid and the resulting solution is treated with a small quantity of sodium hydroxide to produce a white precipitate (B) which redissolves on the addition of excess alkali. The precipitate (B)when ignited in a crucible produces the oxide of the metal(m). The METAL M is Options:
  A) Zn
  B) Cu
  C) Al
  D) Au
  E) Ca
  Show Answer
  The correct answer is A .
• Question 308:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100^oC, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0^oC?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 309: What volume of 0.5 MH₂SO₄ will exactly neutralize 20cm³ of 0.1 MNaOH Solution? Options:
  A) 2.0cm³
  B) 5.0cm³
  C) 6.8cm³
  D) 8.3cm³
  Show Answer
  The correct answer is A .
• Question 310:

  

  In the solubility curve above, water at 98^oC is saturated with KCL and KCIO₃ What is the percentage of KCL impurity in the crystals formed when the solution is cooled to 30 ^oC?

  Options:
  A) 51.5
  B) 45.5
  C) 34.5
  D) 26.5
  Show Answer
  The correct answer is C .