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 1831: Clothes should be properly rinsed with water after bleaching because? Options:
  A) the bleach decolourizes the cothes
  B) chlorine reacts with fabrics during bleaching
  C) the clothes are sterilized during bleaching
  D) hydrogen chloride solution is produced during bleaching
  Show Answer
  The correct answer is D .
• Question 1832: When sulphur (IV) oxide is passed into a solution of sodium hydroxide for a long time, it eventually produces a solution of Options:
  A) NaHSO₄
  B) Na₂SO₃
  C) NaHSO₃
  D) Na₂SO₄
  Show Answer
  The correct answer is B .
• Question 1833: In two separate experiments, 0.36g and 0.71g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20g and 0.40g of X respectively. The data above represents the law of ? Options:
  A) multiple proportion
  B) conservation of mass
  C) constant composition
  D) reciprocal proportion
  Show Answer
  The correct answer is C .
• Question 1834:

  How many grams of H₂SO₄ are necessary for the preparation of 0.175 dm³ of M 6.00 M H₂SO₄?

  (S = 32.06, O = 16.00 H = 1.00)

  Options:
  A) 206.0 g
  B) 103.0 g
  C) 98.1 g
  D) 51.5 g
  Show Answer
  The correct answer is B .
• Question 1835:

  If 10.5g of lead (II) trioxonitrate (V) is dissolved in 20cm³ of distilled water at 18^oC, the solubility of the solute in mol dm^-3 is

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

  Options:
  A) 1.60
  B) 5.25
  C) 16.00
  D) 525.00
  Show Answer
  The correct answer is A .
• Question 1836: Which experiment led to the measurement of the charge on an electron? Options:
  A) Mass spectrometric experiment
  B) Oil-drop experiment
  C) Scattering α - particles
  D) Discharge-tube experiment
  Show Answer
  The correct answer is B .
• Question 1837: The solubilites of different solutes in a given solvent can be compared by Options:
  A) plotting their solubility curves on separete axes
  B) plotting their solubility curves on the same axes
  C) plotting some of the solubility curves on the x-axis and others on the y-axis
  D) plotting their solubility curves on the x-axis only
  Show Answer
  The correct answer is B .
• Question 1838: The chemical reaction which takes place at the anode (positive electrode) in electrolysis is? Options:
  A) oxidation
  B) hydrolysis
  C) dissociation
  D) reduction
  E) disproportionation
  Show Answer
  The correct answer is A .
• Question 1839:

  200cm³ each of 0.1M solutions of lead (II) trioxonitrate (V) and hydrochloric acid were mixed. Assuming that lead (II) chloride is completely insoluble, calculate the mass of lead (II) chloride that will be precipitated.

  [Pb = 207, Cl= 35.5, N = 14, O = 16]

  Options:
  A) 2.78g
  B) 5.56g
  C) 8.34g
  D) 11.12g
  Show Answer
  The correct answer is B .
• Question 1840: When sodium chloride and metallic sodium are each dissolved in water Options:
  A) both processes are exothermic
  B) both processes are endothermic
  C) the dissolution of metallic sodium is endothermic
  D) the dissolution of metallic sodium is exothermic
  E) the dissolution of sodium chloride is explosive
  Show Answer
  The correct answer is D .