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 151: If concentrated sulphric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mas of carbon. In this reaction, concentrated sulphuric acid is acting as ? Options:
  A) a drying agent
  B) an oxidizing agent
  C) a dehydrated agent
  D) a reducing agent
  E) a hydrolysing agent
  Show Answer
  The correct answer is C .
• Question 152:

  An organic compound which decolorizes bromine water is likely to be?

  Options:
  A) C${}_3$H${}_8$
  B) C${}_2$H${}_6$
  C) C${}_4$H${}_{1}0$
  D) C${}_2$H${}_4$
  Show Answer
  The correct answer is D .
• Question 153:

  Calculate the volume in cm³ of oxygen evolved at s.t.p when a current of 5A is passed through acidified water for 193s?

  [F = 96500 C mol¹. Molar volume of a gas at s.t.p = 22.4dm³]

  Options:
  A) 0.056dm³
  B) 0.224dm³
  C) 224.000dm³
  D) 56.000dm³
  Show Answer
  The correct answer is A .
• Question 154:

  Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5.

  The relative abundance of the isotope of mass number 37 is?

  Options:
  A) 20
  B) 25
  C) 50
  D) 75
  Show Answer
  The correct answer is B .
• Question 155: 2 - methyl propan -2- ol is an example of a Options:
  A) primary alkanol
  B) secondary alkanol
  C) tertiary alkanol
  D) quartenary alkanol
  Show Answer
  The correct answer is C .
• Question 156: Beryllium and aluminium have similar properties because they Options:
  A) are both metals
  B) belong to the same group
  C) belong to the same period
  D) are positioned diagonally to each other
  Show Answer
  The correct answer is D .
• Question 157:

  Na₂S₂O_3(aq) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l)

  Which of the following would introduce the greatest increase in the rate of the chemical reaction above?

  Options:
  A) An increase in temperature and decrease in the concentration of the reactant
  B) A decrease in the volume and increase in the pressure of the reactant
  C) A decrease in the temperature and an incease in the concentration of the reactant
  D) An increase in temperature and an increase in the concentration of the reactant
  Show Answer
  The correct answer is D .
• Question 158: Which of the following is used to study the arrangement of particles in crystal lattices? Options:
  A) Alpha-particles
  B) Beta-particles
  C) Gamma-rays
  D) X-rays
  Show Answer
  The correct answer is D .
• Question 159: The correct order of increasing oxidation number of the transition metal ions for the compounds K₂Cr₂O₇, V₂O₅ and KMnO₄ is Options:
  A) V₂O₅< K_2Cr2O₇< KMnO₄
  B) K₂Cr₂O₇< KMnO_{4 < V2O5}
  C) KMnO₄< K_2Cr2O₇< V_2O5
  D) KMnO₄< V_2O5< K_2Cr2O₇
  Show Answer
  The correct answer is A .
• Question 160:

  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 .