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 201: Calculate the relative molecular mass of Limestone CaCO3, (Ca = 40, C =12, O = 16) Options:
  A) 56
  B) 100
  C) 76
  D) 90
  Show Answer
  The correct answer is B .
• Question 202: The enzymes responsible for converting sucrose into two simple isomeric sugars is Options:
  A) maltase
  B) amylase
  C) invertase
  D) lactase
  Show Answer
  The correct answer is C .
• Question 203: A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The sample contains Options:
  A) Cl^-
  B) NO₃^-
  C) SO₃^2-
  D) SO₄^2-
  Show Answer
  The correct answer is C .
• Question 204: An example of a strong electrolyte is? Options:
  A) ethyl acetate
  B) ethanol
  C) glucose
  D) sodium formate
  E) formic acid
  Show Answer
  The correct answer is D .
• Question 205:

  The equilibrium reaction between copper (l) chloride and chlorine at 25^oC and 1 atmosphere is represented by the equation:

  2CuCl +Cl₂ ⇌ 2 CuCl₂ ∆H = - 166 KJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

  Options:
  A) more CuCl is formed at 40^oC
  B) more CuCl₂ is formed at 10^oC
  C) Less CuCl₂ is formed at 10^oC
  D) there is no change in the amount of CuCl₂ formed at 40^oC and10^oC
  E) more CuCl is consumed at 40^oC
  Show Answer
  The correct answer is B .
• Question 206:

  What mass of K₂CrO₄ is required to prepare 250cm³ of 0.020 mol dm³ solution?

  [K₂CrO₄ = 194.2g mol^-1]

  Options:
  A) 0.97g
  B) 9.70g
  C) 19.42g
  D) 97.10g
  Show Answer
  The correct answer is A .
• Question 207:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 208: Which of the following solutions will give a white precipitate with barium chloride solution and a green flame test? Options:
  A) Na₂SO₄
  B) CuSO₄
  C) CaSO₄
  D) CaCI₂
  E) (NH₄)₂SO₄
  Show Answer
  The correct answer is B .
• Question 209:

  According to the kinetic theory of gases, the pressure exerted by a gas is due to

  Options:
  A) The vibrations of gas particles.
  B) The weight of the gas particles
  C) The attractive forces between gas particles
  D) The collisions of gas particles with the container walls
  Show Answer
  The correct answer is D .
• Question 210:

  What volume of oxygen is produced from the decomposition of 2 mole of KCIO₃ at s.t.p?

  [Molar volume of a gas at s.t.p = 22.4 dm³]

  Options:
  A) 22.4 dm³
  B) 33.6 dm³
  C) 44.8 dm³
  D) 67.2 dm³
  Show Answer
  The correct answer is D .