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 981: Which of the following will change when a catalyst is added to a chemical reaction? Options:
  A) The activation energy
  B) The potential energy of the reactants
  C) The heat of the reaction
  D) the potential energy of the product
  Show Answer
  The correct answer is A .
• Question 982: Which of the following contains two amphoteric oxides? Options:
  A) sodium oxide, Zinc oxide , Magnesium oxide
  B) Aluminium oxide, Calcium oxide, Zinc oxide
  C) Potassium oxide, Lithium oxide, Carbon monoxide
  D) Silver oxide, Lead oxide, Sodium oxide
  E) Sulphur dioxide, Aluminium oxide, Carbon monoxide
  Show Answer
  The correct answer is B .
• Question 983:

  Consider the reaction

  A${}_{(s)}$ + 2B${}_{(g)}$ → 2C${}_{(aq)}$ + D${}_{(g)}$

  What will be the effect of a decrease in pressure on the reaction?

  Options:
  A) the equilibrium will shift
  B) rate of forward reaction will increase
  C) rate of backward reaction will increase
  D) rates of forward and backward reaction are not affected
  Show Answer
  The correct answer is B .
• Question 984: In the electrolytic extraction of aluminum, the function of the molten cryolite is to Options:
  A) precipitate aluminium hdroxide
  B) lower the melting point of aluminium oxide
  C) act as a raw materials
  D) act as a solvent
  Show Answer
  The correct answer is B .
• Question 985: The colour imparted to a flame by calcuium ion is Options:
  A) green
  B) blue
  C) brick-red
  D) yellow
  E) lilac
  Show Answer
  The correct answer is C .
• Question 986: Polystyrene is widely used as packaging materials for fragile objects during transportation because of its Options:
  A) ligjtness
  B) low density
  C) high density
  D) high compressibility
  Show Answer
  The correct answer is D .
• Question 987:

  The Sulphide which is insoluble in dilute hydrochloric acid is

  Options:
  A) FeS
  B) CuS
  C) ZnS
  D) Na2S
  Show Answer
  The correct answer is B .
• Question 988:

  

  The diagram represents

  Options:
  A) A spontaneous reaction
  B) An exothermic reaction
  C) A non-spontaneous
  D) An endothermic reaction
  Show Answer
  The correct answer is C .
• Question 989: A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The sample contains Options:
  A) Cl^-
  B) NO₃^-
  C) SO₃^2-
  D) SO₄^2-
  Show Answer
  The correct answer is C .
• Question 990:

  Which quantum divides shells into orbitals?

  Options:
  A) Spin
  B) Principal
  C) Azimuthal
  D) Magnetic
  Show Answer
  The correct answer is C .