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 2201:

  Some copper (ll) sulphate pentahydrate (CuSO₄ 5H₂O), was heated at 120 ^oC with the following results. Wt of crucible = 10.00 g; Wt of crucible + CuSO₄ 5H₂O =14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystalization were lost?

  [H = 1, Cu = 63.5, O = 16, S = 32]

  Options:
  A) 1
  B) 2
  C) 3
  D) 4
  E) 5
  Show Answer
  The correct answer is D .
• Question 2202:

  

  The ∆H for the reaction represented by the energy profile above is

  Options:
  A) -100 kJ mol-^-1
  B) + 100 kJ mol^-1
  C) +50 kJ mol^-1
  D) -50 kJ mol^-1
  Show Answer
  The correct answer is D .
• Question 2203:

  

  The solubility curve of a solid X (molecular mass = 160) is as show above 1,000 cm³ of a saturated solution of X at 80^oC. The weight of X crystalized out would be

  Options:
  A) 10 g
  B) 12 g
  C) 14 g
  D) 16 g
  E) 18 g
  Show Answer
  The correct answer is D .
• Question 2204: In which of the following processes is iron being oxidized?1 Fe + H₂SO₄ → FeSO₄ +H₂2 FeSO₄ + H₂S → FeS + H₂SO₄3 2FeCI₂ + Cl₂ → 2FeCl₃4 2FeCl₃ + SnCl₂ + → 2FeCl₂ + SnCl₄ Options:
  A) 1 only
  B) 2 only
  C) 3 only
  D) 1 and 3
  E) 2 and 4
  Show Answer
  The correct answer is D .
• Question 2205: The relative atomic mass of a naturally occurring lithium consisting of 90% Li and 10% Li is Options:
  A) 6.9
  B) 7.1
  C) 6.2
  D) 6.8
  Show Answer
  The correct answer is C .
• Question 2206:

  2H₂O _(l) + 2F_2(g) → 4HF_(aq) + O_2(g).

  In the reaction above, the substance that is being reduced is

  Options:
  A) O_2(g)
  B) H₂O_(l)
  C) F_2(g)
  D) HF_(aq)
  Show Answer
  The correct answer is C .
• Question 2207: An effect of thermal pollution on water bodies is that the Options:
  A) volume of water reduces
  B) volume of chemical waste increase
  C) level of oxides of nitrogen increase
  D) level of oxygen reduces
  Show Answer
  The correct answer is D .
• Question 2208: Ethanol reacts with aqueous sodium mono-oxoio date (l) to give a bright yellow solid with a characteristic smell. The product is? Options:
  A) trichloromethane
  B) triodomethane
  C) iodoethane
  D) ethanal
  Show Answer
  The correct answer is B .
• Question 2209:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  The molecular formula of X is

  Options:
  A) C₁₂H₂₂O₁₁
  B) C₆H₁₂O₆
  C) C₃H₆O ₃
  D) C₇H₁₄O₇
  E) C₁₂H₆O₄
  Show Answer
  The correct answer is B .
• Question 2210: Alkanoates are formed by the reaction of alkanoic acid with? Options:
  A) Alkyl halides
  B) alkanols
  C) ethers
  D) sodium
  Show Answer
  The correct answer is B .