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 401: Which of the following gases is the most dangerous pollutant? Options:
  A) Hydrogen sulphide
  B) Carbon (lV) oxide
  C) Sulphur (lV) oxide
  D) Carbon (ll) oxide
  Show Answer
  The correct answer is D .
• Question 402:

  How many grams of methylacetylene (propyne) CH₃ - C Ξ CH will completely discharge the colour of 8g of bromine?

  (Br = 80, C = 12, H = 1)

  Options:
  A) 0.5
  B) 1.0
  C) 2.0
  D) 3.0
  E) 4.0
  Show Answer
  The correct answer is B .
• Question 403:

  Which of the following gases will rekindle a brightly splint?

  Options:
  A) NO${}_2$
  B) NO
  C) N${}_2$O
  D) CL${}_2$
  Show Answer
  The correct answer is C .
• Question 404:

  117.0g of sodium chloride was dissolved in the solubility in 1.0dm³ of distilled water at 25^oC. Determine the solubility in mol dm^-3 of sodium chloride at that temperature

  [Na = 23, Cl = 35.5]

  Options:
  A) 1.0
  B) 2.0
  C) 3.0
  D) 4.0
  Show Answer
  The correct answer is B .
• Question 405: Calculate the amount in moles of a gas which occupies 10.5 dm³ at 6 atm and 30^oC [R = 082 atm dm³ K^-1 mol^-1] Options:
  A) 2.536
  B) 1.623
  C) 4.736
  D) 0.394
  Show Answer
  The correct answer is A .
• Question 406:

  A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?

  Options:
  A) sulphur (lV) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
  Show Answer
  The correct answer is A .
• Question 407:

  A given amount of gas occupies 10.0dm5 at 4atm and 273°C. The number of moles of the gas present is [Molar volume of gas at s.t.p = 22.4dm${}^3$]

  Options:
  A) 0.89 mol
  B) 1.90 mol
  C) 3.80 mol
  D) 5.70 mol
  Show Answer
  The correct answer is A .
• Question 408: A concentrated solution containing H⁺, Cu²⁺,OH^- and CI^- was electrolysed using platiunm electrodes which of the ions will be discharged at the cathods? Options:
  A) H⁺
  B) Cu²⁺
  C) OH^-
  D) CI^-
  Show Answer
  The correct answer is B .
• Question 409:

  What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours, through molten magnesium chloride?
  [1 faraday = 96500C, Mg = 24]

  Options:
  A) 1.12g
  B) 4.48g
  C) 1.80g
  D) 2.00g
  Show Answer
  The correct answer is C .
• Question 410: The tincture of iodine means iodine dissolved in Options:
  A) ethanol
  B) bromine chloride
  C) chlorine water
  D) water
  Show Answer
  The correct answer is A .