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 1241:

  2Cl_2(g) + 2H₂O_(g) 4HCl_(g) + O_2(g)

  ∆H° = +115KJ mol^-1. In the above equilibrium reaction, a decrease in temperature will?

  Options:
  A) favour the reverse reaction
  B) favour the forward reaction
  C) have no effect on the equilibrium state
  D) double the rate of the reverse raection
  Show Answer
  The correct answer is A .
• Question 1242:

  2SO${}_2$ ${}_{(g)}$+ O${}_2$ ${}_{(g)}$ ↔ 2SO${}_3$${}_{(g)}$ ΔH = -395.7kJmol${}^{-1}$

  In the equation, an increase in temperature will shift the equilibrium position to the

  Options:
  A) left and equilibrium constant decreases
  B) left and equilibrium constant increases
  C) right and equilibrium constant increases
  D) right and equilibrium constant decreases
  Show Answer
  The correct answer is A .
• Question 1243: Consider the following exothermic reaction 2SO₂(g) + O₂(g) = 2SO₃ (g) . If the temperature of the reaction is reduced from 800_oC to 500_oC, and no other change takes place, then Options:
  A) the reaction rate increases
  B) concentration of SO₃ decreases
  C) concentration of SO₃ increases
  D) SO₂ gas becomes unreactive
  E) O₂ gas becomes unreactive
  Show Answer
  The correct answer is C .
• Question 1244: Ethanol reacts with aqueous sodium mono-oxoio date (l) to give a bright yellow solid with a characteristic smell. The product is? Options:
  A) trichloromethane
  B) triodomethane
  C) iodoethane
  D) ethanal
  Show Answer
  The correct answer is B .
• Question 1245: The gas that is used for the treatment of cancer is Options:
  A) Neon
  B) Radon
  C) Xenon
  D) Argon
  Show Answer
  The correct answer is B .
• Question 1246: Diffusion is slowest in solid particles than in particles of liquid and gases because Options:
  A) solid particles have more kinetic energy than the particles of liquid and gases
  B) solid particles have less kinetic energy than the particles of liqiud and gases
  C) solid particles have less restriction in their movement than liquid and gas particles
  D) the particles in solids are far apart and the cohesive forces between them are negligible
  Show Answer
  The correct answer is B .
• Question 1247:

  If a reaction is exothermic and there is a great disorder, it means that

  Options:
  A) the reaction is static
  B) the reaction is in a state of equilibrium
  C) there will be a large increase in free energy
  D) there will be a large decrease in free energy
  Show Answer
  The correct answer is D .
• Question 1248:

  How many atoms are present in 6.0g of magnesium?

  [Mg = 24, N_A = 6.02 x 10²³ mol^-1]

  Options:
  A) 1.20 x 10²²
  B) 2.41 x 10²²
  C) 1.51 x 10²³
  D) 3.02 x 10²³
  Show Answer
  The correct answer is C .
• Question 1249: A trihydric alkanol is Options:
  A) Glycerol
  B) Phenol
  C) Glycol
  D) Ethanol
  Show Answer
  The correct answer is A .
• Question 1250: The difference between colloides and and suspensions is brought out clearly by the fact that while colloids? Options:
  A) do not scatter light, suspensions do
  B) can be separated by filtration, suspension cannot be so separated
  C) can be separated by a membrane, suspensions cannot
  D) do not settle out on standing, suspensions do
  Show Answer
  The correct answer is D .