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 641: The postulate of Dalton's atomic theory which still holds is that Options:
  A) atoms can neither be created nor destroyed
  B) the particles of the same element are exactly alike
  C) particles of different elements combine in simple whole number ratio
  D) all elemets are made of small indivisible particles
  Show Answer
  The correct answer is A .
• Question 642:

  Which of the following is an example of a primary cell?

  Options:
  A) Alkaline battery
  B) Nickel-cadmium battery
  C) Lead-acid battery
  D) Lithium-ion battery
  Show Answer
  The correct answer is A .
• Question 643: A mixture of iodine and sulphur crystals can be separated by treatment with Options:
  A) Water to filter off sulphur
  B) carbon (IV) sulphide to filter off iodine
  C) ethanoic acid to filter off sulphur
  D) methanol to filter off iodine
  Show Answer
  The correct answer is B .
• Question 644:

  16.55g of lead (ll) trioxonitrate (V) was dissolved in 100g of distilled water at 20^oC, calculate the solubility of the solute in moldm-³

  [Pb = 207, N = 14, O = 16]

  Options:
  A) 0.05 g
  B) 2.00 g
  C) 1.00 g
  D) none of the above
  Show Answer
  The correct answer is D .
• Question 645: When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant? Options:
  A) 2SO_3(g) ↔ 2SO_2(g) + O_2(g)
  B) 2CO_2(g) ↔ 2CO_(g) + O_2(g)
  C) 2H_2(g) + O_2(g) ↔ 2H₂O_(g)
  D) 2NO_(g) ↔ N_2(g) + O_2(g)
  Show Answer
  The correct answer is C .
• Question 646:

  The sulphide that is commonly used in coating electric fluorescent tubes is?

  Options:
  A) iron(ii)Sulphide
  B) tin(ii)sulphide
  C) Zinc Sulphide
  D) lead(iv) Sulphide
  Show Answer
  The correct answer is C .
• Question 647: 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 648: A side effect of soft water is that Options:
  A) it gives offensive taste
  B) excess calcium is precipitated
  C) it attacks lead contained in pipes
  D) it encourage the growth of bacteria
  Show Answer
  The correct answer is C .
• Question 649: 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 650: Detergents have the general formula? Options:
  A) R(CH₂)_nOH
  B) RSO₃^-Na⁺
  C) RSO^-₂Na⁺
  D) RSO₂H
  Show Answer
  The correct answer is B .