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 31: the vapour density of a gas may be defined as Options:
  A) the mass of a unit volume of the gas compared to an equal volume of water vapour
  B) the mass of a unit volume of the gas compared to an equal volume of hydrogen
  C) the mass of a unit volume of the gas compared to an equal volume of oxygen
  D) the mass of a unit volume of the gas minus the vapour pressure of water
  E) two times the relative molecular mass of the gas
  Show Answer
  The correct answer is B .
• Question 32: The saponification of an alkanoate to produce soap and alkanol involves Options:
  A) dehydration
  B) esterification
  C) hydrolysis
  D) oxidation
  Show Answer
  The correct answer is C .
• Question 33:

  What volume of gas is evolved at S.t.p if 2g of calcium trioxocarbonate (IV) is added to a solution of hydrochloric acid?

  [Ca = 40, C = 12, O = 16, Cl = 35.5, H = 1 Molar volume of agas at s.t.p = 22.4 dm³

  Options:
  A) 112 cm²
  B) 224 cm²
  C) 448 cm²
  D) 2240 cm²
  Show Answer
  The correct answer is C .
• Question 34: NH_3(g) + HCl_(s) → NH ₄Cl _(s)The entropy change in the system above is Options:
  A) positive
  B) zero
  C) negative
  D) intermediate
  Show Answer
  The correct answer is C .
• Question 35:

  In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm${}^3$ of 1.25 molar tetraoxosulphate (vi) acid?

  Options:
  A) 25cm${}^3$
  B) 10cm${}^3$
  C) 20cm${}^3$
  D) 50cm${}^3$
  Show Answer
  The correct answer is D .
• Question 36: When iron is exposed to moisture and it rusts, the value of ΔG for the reaction is Options:
  A) neutral
  B) zero
  C) positive
  D) negative
  Show Answer
  The correct answer is D .
• Question 37: The solution with the lowest pH value is Options:
  A) 5 ml of (m/10) HCL
  B) 10 ml of (m/10) HCL
  C) 15 ml of (m/5) HCL
  D) 20 ml of (m/8) HCL
  Show Answer
  The correct answer is A .
• Question 38: What process would coal undergo to give coal gas, coal tar, ammoniacal liquor and coke? Options:
  A) Steam distillation
  B) Destructive distillation
  C) Liquefaction
  D) Hydrolysis
  Show Answer
  The correct answer is B .
• Question 39: 10cm³ of CO is mixed and sparked with 100cm³ of air containing 21% O₂. If all the volumes measured at S.T.P. the volume of resulting gases would be? Options:
  A) 90cm³
  B) 100cm³
  C) 105cm³
  D) 110cm³
  E) 115cm³
  Show Answer
  The correct answer is C .
• Question 40: If the elements X and Y have atomic numbers 11 and 17 respectively, what type of bond can they form? Options:
  A) Dative
  B) Covalent
  C) Lonic
  D) Metallic
  Show Answer
  The correct answer is C .