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 191: A substance that is used as a ripening agent for fruits is Options:
  A) ethene
  B) propene
  C) methane
  D) butane
  Show Answer
  The correct answer is A .
• Question 192: When 50cm³ of a saturated solution of sugar (molar mass 342.0g) at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 10.0 moles dm^-3
  B) 7.0 moles dm^-3
  C) 3.5 moles dm^-3
  D) 2.0 moles dm^-3
  Show Answer
  The correct answer is D .
• Question 193: 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 194:

  MnO_2(s) + xHCl_(aq) → MnCl_2(aq) + yH₂O_(l) + zCl_2(g)

  In theequation above, what are the values of x, y and z respectively

  Options:
  A) 2, 1, 2
  B) 4, 1, 2
  C) 4, 2, 1
  D) 1, 2, 1
  Show Answer
  The correct answer is C .
• Question 195:

  CO_(g) + H₂ O_(g) → CO_2(g) + H_2(g)

  Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) and CO_(g) in KJ mol ^-1 are - 394 -242 and - 110 respectively.

  Options:
  A) + 262 KJ mol ^-1
  B) - 262 KJ mol ^-1
  C) + 42 KJ mol ^-1
  D) - 42 KJ mol ^-1
  Show Answer
  The correct answer is D .
• Question 196: Liquid X, reacts with sodium trioxocarbonate (IV) (Na₂CO₃) to give a gas which turns calcium chloride solution milky X is Options:
  A) Na₂SO₄(aq)
  B) Kl (aq)
  C) an alkali
  D) an acid
  E) a hydrocarbon
  Show Answer
  The correct answer is D .
• Question 197: According to the kinetic theory an absence in temperature causes the kinetic energy of particles to Options:
  A) decrease
  B) increase
  C) remain constant
  D) be zero
  Show Answer
  The correct answer is C .
• Question 198:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 199: which of these metals CANNOT replace hydrogen from alkaline solutions? Options:
  A) Aluminium
  B) Zinc
  C) Tin
  D) Iron
  Show Answer
  The correct answer is A .
• Question 200: Which of the following substances is not a salt? Options:
  A) Aluminium oxide
  B) Sodium hydrogentrioxosulphate (V)
  C) Sodium trioxocarbonate (V)
  D) Zinc chloride
  Show Answer
  The correct answer is A .