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 1421: The constituent of air that acts as a diluent is Options:
  A) nitrogen
  B) carbon (IV) oxide
  C) noble gases
  D) oxygen
  Show Answer
  The correct answer is A .
• Question 1422: Which of the following acts as both a reducing and an oxidizing agent? Options:
  A) H₂
  B) SO₂
  C) H₂S
  D) CO₂
  Show Answer
  The correct answer is B .
• Question 1423: Alkanols have the general molecular formula Options:
  A) C₁H_2n-2
  B) C₁H_2n-1CHO
  C) C₁H_2n-2OH
  D) C₂H_2n+1OH
  Show Answer
  The correct answer is D .
• Question 1424: In the preparation of oxygen by heating KClO₃ in the presence of MnO₂, only moderate heat is needed because the catalyst acts by Options:
  A) lowering the pressure of the reaction
  B) increasing the surface area of the reactant
  C) increase the rate of the reaction
  D) lowering the energy barrier of the reaction
  Show Answer
  The correct answer is D .
• Question 1425: Which of the following gases may not be dried with concentrated sulphuric acid? Options:
  A) HCl
  B) N₂
  C) Cl₂
  D) SO₂
  E) NH₃
  Show Answer
  The correct answer is E .
• Question 1426: What amount of mercury would be liberated if the same quantity of electricity that liberates 0.65g of zinc is applied? Options:
  A) 2.01g
  B) 1.00g
  C) 4.02g
  D) 8.04g
  Show Answer
  The correct answer is C .
• Question 1427: The principle of column chromatography is based on the ability of the constituents to Options:
  A) move at different speeds in the column
  B) dissolve in each other in the column
  C) react with the solvent in the column
  D) react with each other in the column
  Show Answer
  The correct answer is A .
• Question 1428: What weight of sodium hydroxide is required to make 500 cm³ of 0.2 M solution?(Na = 23, O = 16, H = 1) Options:
  A) 40 g
  B) 20 g
  C) 10 g
  D) 4 g
  E) 2 g
  Show Answer
  The correct answer is D .
• Question 1429:

  

  Use the graph above to answer this question. The structure of cis-2-butene is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 1430:

  Which of the following is a physical change?

  Options:
  A) Exposing white phosphorus to air
  B) Burning kerosene
  C) Dissolving calcium in water
  D) Freezing ice cream
  Show Answer
  The correct answer is D .