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 731: In which of the following are the aqueous solutions of each of the substances correctly arranged in order to decreasing acidity? Options:
  A) Ethanoic acid, milk or magnesia, sodium chloride, hydrochloric acid and sodium hydroxide
  B) Ethanoic acid, hydrochloric acid, milk of magnesia, sodium chloride and sodium chloride and sodium hydroxide
  C) Hydrochloride acid, ethanol acid, sodium chloride, milk of magnesia and sodium hydroxide
  D) Hydrochloride acid, sodium hydroxide sodium chloride, ethanol acid, and milk of magnesia
  Show Answer
  The correct answer is C .
• Question 732: The colour of litmus in an alkaline medium is Options:
  A) Red
  B) Yellow
  C) Pink
  D) Blue
  Show Answer
  The correct answer is D .
• Question 733:

  C_(s) + H₂O_(g) → H_2(g) + CO_2(g)

  ΔG for the reaction above at 1300k is -43KJ. At this temperature, the reaction is

  Options:
  A) not feasible
  B) at equilibrium
  C) feasible
  D) exothermic
  Show Answer
  The correct answer is C .
• Question 734: The carbon atoms on ethane are? Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp²d hybridized
  D) sp hybridized
  Show Answer
  The correct answer is B .
• Question 735: In the chemical reaction A + B $\to$ C + D, more of D is formed? Options:
  A) if the concentrated of A is reduced
  B) if the concentrated of B is reduced
  C) if the concentrated of C is reduced
  D) if the concentration of C is increased
  E) if D is continuously removed from the reaction mixture
  Show Answer
  The correct answer is E .
• Question 736: In a water body, too much sewage leads to Options:
  A) a decrease in the temperature of the water which cause in death of aquatic animals
  B) an increase in the number of aquatic animals in the water
  C) an increase in the bacterial population which reduces the level of oxygen in the water
  D) a decrease in the bacterial population which increases the level of oxygen in the water
  Show Answer
  The correct answer is C .
• Question 737:

  10.0 dm³ of air containing H₂S as an impurity was passed through a solution of Pb(NO₃)₂ until all the H₂S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO₃)₂ + H₂S → PbS + 2HNO₃ the percentage by volume of hydrogen sulphide in the air is?

  (Pb = 207, S = 32, GMV at s.t.p = 22.4dm³)

  Options:
  A) 50.2
  B) 47.0
  C) 4.70
  D) 0.47
  Show Answer
  The correct answer is C .
• Question 738:

  5SO_2(g) + 2KMnO_4(aq) + 2H₂O_(l) → K₂SO₄ + 2MnSO_4(aq) + 2H₂SO_4(aq)

  In the reaction above, the products give a

  Options:
  A) purple solution
  B) purple precipitate
  C) colourless precipitate
  D) colourless solution
  Show Answer
  The correct answer is D .
• Question 739: A heterogenous mixture can be defined as any mixture Options:
  A) of a solute nd a solvent
  B) whose cmposition is uniform
  C) whose composition is not uniform
  D) formed by solids and liquids
  Show Answer
  The correct answer is C .
• Question 740:

  The solubility of the solids that dissolves in a given solvent with the liberation of heat will

  Options:
  A) increase with an increase in temperature
  B) decrease with an increase in temperature
  C) decrease with a decrease in temperature
  D) not be affected by changes in temperature
  Show Answer
  The correct answer is A .