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 11: What is the percentage of sulphur in sulphur (IV) oxide? Options:
  A) 66%
  B) 25%
  C) 40%
  D) 50%
  Show Answer
  The correct answer is D .
• Question 12: In the reaction of oxygen with hydrogen to produce water, which of the following statements is true? Options:
  A) One atom of hydrogen reacts with two atoms of oxygen to give one molecule of water
  B) Two atoms of hydrogen react with two atoms of oxygen to give two molecules of water
  C) One molecule of oxygen reacts with one molecule of hydrogen to give two molecules of water
  D) One molecule of hydrogen reaccts with two molecules of oxygen to give three molecules of water
  E) One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
  Show Answer
  The correct answer is E .
• Question 13: Which of the following acts as both a reducing and an oxidizing agent? Options:
  A) H₂
  B) SO₂
  C) H₂S
  D) C
  Show Answer
  The correct answer is B .
• Question 14: In the periodic table, what is the property that decreases along the periodic and increases down the group? Options:
  A) Atomic number
  B) Electron affinity
  C) Ionization potential
  D) Atomic radius
  Show Answer
  The correct answer is D .
• Question 15: Which of the following is TRUE of Le Chatelier's Principle for an exothermic reaction? Options:
  A) Increase in temperature will cause an increase in the equilibrium constant
  B) Increase in temperature will cause a decrease in the equilibrium constant
  C) Addition of a catalyst will cause an increase in the equilibrium constant
  D) Addition of a catalyst will cause a decrease in the equilibrium constant
  Show Answer
  The correct answer is B .
• Question 16:

  

  In the diagram above. X is

  Options:
  A) SO₃
  B) SO₂
  C) S
  D) H₂S
  Show Answer
  The correct answer is B .
• Question 17: In the electrolysis of brine, the anode is Options:
  A) platinum
  B) copper
  C) zinc
  D) carbon
  Show Answer
  The correct answer is D .
• Question 18: A particle that contains 8 proton, 9 neutrons and 7 electrons could be written as? Options:
  A) O
  B) O⁺
  C) O⁺
  D) O^-
  Show Answer
  The correct answer is B .
• Question 19:

  The electronic configuration of element Z is 1s${}^2$ 2s${}^2$ 2p${}^6$ 3s${}^2$ 3p${}^1$. What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion.

  Options:
  A) Z${}_3$(SO${}_4$)${}_2$
  B) ZSO${}_4$
  C) Z${}_2$ SO${}_4$
  D) Z${}_2$(SO${}_4$)${}_3$
  Show Answer
  The correct answer is D .
• Question 20:

  To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?

  Options:
  A) Passed over heated copper(ii)oxide
  B) Bubbled through water
  C) Bubbled through conc H${}_2$SO${}_4$
  D) Bubbled through conc NAOH
  Show Answer
  The correct answer is D .