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 311: When 50cm² of a saturated solution of sugar of molar mass 342 g at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 2.0 mol dm^-3
  B) 3.5 mol dm^-3
  C) 7.0 mol dm^-3
  D) 10.0 mol dm^-3
  Show Answer
  The correct answer is A .
• Question 312:

  The scientist who stated that matter can be converted into energy is?

  Options:
  A) Boyle
  B) Lavoiser
  C) Avogadro
  D) Einstein
  Show Answer
  The correct answer is D .
• Question 313:

  

  How many more isomers of the compound above can be obtained ?

  Options:
  A) 5
  B) 4
  C) 3
  D) 2
  Show Answer
  The correct answer is B .
• Question 314:

  16.8 g of sodium hydrogen trioxocarbonate (IV) is completely decomposed by heat. Calculate the volume of carbon(IV) oxide given off s.t.p

  [Na 23, C = 12, O = 16, H = 1, Molar volume of a gas at s.t.p = 22.4 dm³]

  Options:
  A) 22.40 dm³
  B) 11.20 dm³
  C) 2.24 dm³
  D) 1.12 dm³
  Show Answer
  The correct answer is C .
• Question 315:

  Calculate the percentage by mass of nitrogen in calcium trioxonitrate (V).
  [Ca = 40, N = 14, O = 16]

  Options:
  A) 8.5%
  B) 13.1%
  C) 17.1%
  D) 27.6%
  Show Answer
  The correct answer is C .
• Question 316: The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0) Options:
  A) N₂O₂
  B) NO
  C) NO₂
  D) N₂O
  E) N₂O₃
  Show Answer
  The correct answer is C .
• Question 317:

  Which of the following equimolar solutions, Na₂CO₃ Na₂ SO

  ₄CI FeCI₃ CH₃COONa,

  Have pH greater than 7?

  Options:
  A) FeCI ₃ and NH ₄CI
  B) Na₂CO₃, CH₃COONa and Na,Na₂SO₄
  C) Na₂CO₃ and CH₃COONa
  D) FeCI₃, CH₃COONa and NH₄CI
  Show Answer
  The correct answer is C .
• Question 318: The fraction of crude oil used as jet fuel is Options:
  A) refinery gas
  B) diesel oil
  C) kerosine
  D) gasoline
  Show Answer
  The correct answer is C .
• Question 319: Helium atoms are chemically unreactive because Options:
  A) there are no electrons around the nucleus
  B) the number of protons equals the number of electrons
  C) there are equal number of protons and neutrons in the nucleus
  D) the outer electron shell is completely filled
  E) the atoms contain only protons
  Show Answer
  The correct answer is D .
• Question 320:

  If a given quantity of electricity liberates 0.65g of Zn²⁺, what amount of Hg²⁺ would be liberated by the same quantity of current?

  [Zn = 65, Hg = 201]

  Options:
  A) 1.00g
  B) 2.10g
  C) 4.02g
  D) 8.04g
  Show Answer
  The correct answer is B .