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 241: When excess ethanol is heated to 145^oC in the presence of concentrated H₂SO₄, the product is Options:
  A) ethyne
  B) diethyl sulphate
  C) diethyl ether
  D) acetone
  Show Answer
  The correct answer is C .
• Question 242:

  What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute.

  [Na = 23, N = 14, O = 16]

  Options:
  A) 1.7 litres
  B) 0.420 litres
  C) 0.588 litres
  D) 2.35 litres
  Show Answer
  The correct answer is C .
• Question 243:

  L . Evaporation. ll. Sublimation. lll. Diffusion. IV. Brownian motion.

  Which of the above can correctly be listed as evidences for the particulate nature of matter?

  Options:
  A) I and lll only
  B) ll and lV only
  C) l, ll and lll only
  D) l, ll, lll and lV
  Show Answer
  The correct answer is D .
• Question 244: A pair of compounds that can be used to generate a gas which has physiological effect on human beings is Options:
  A) sodium trioxonitrate (V) and calcium chloride
  B) sodium dioxonitrate (III) and ammonium chloride
  C) sodium trioxonitrate (V) and ammonium chloride
  D) sodium dioxonitrate (III) and potassium chloride
  Show Answer
  The correct answer is A .
• Question 245:

  

  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 .
• Question 246: The compounds CH₃CH₂CHO and CH₃COCH₃ can be distinguished from each other using Options:
  A) Dilute ammonia
  B) Benedict's solution
  C) Tollen's reagent
  D) Sodium hydroxide solution
  Show Answer
  The correct answer is C .
• Question 247: Which of the following statements is incorrect? Options:
  A) Calcium reacts with water to form calcium
  B) Magnesium reacts very slowly with water but faster with warm water
  C) Iron will not react with water in the absence of air
  D) Sodium reacts with water
  E) Copper reacts with steam
  Show Answer
  The correct answer is E .
• Question 248: Which of these require crystallization most? Options:
  A) Drug making
  B) Cement making
  C) Paint making
  D) Perfume making
  Show Answer
  The correct answer is A .
• Question 249: The method that can be used to convert hard water to soft water is Options:
  A) chlorination
  B) passage over activated charcoal
  C) the use of an ion-exchange resin
  D) aeration
  Show Answer
  The correct answer is C .
• Question 250:

  What happens to the position of equilibrium, if a reversible exothermic reaction is subjected to a decrease in temperature?

  Options:
  A) The position of equilibrium shifts to the left
  B) The position of equilibrium shifts to the right.
  C) The position of equilibrium remains unchanged
  D) The reaction stops
  Show Answer
  The correct answer is B .