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 501: The property which makes alcohol soluble in water is the Options:
  A) boiling point
  B) hydrogen bonding
  C) ionic character
  D) covalent nature
  Show Answer
  The correct answer is B .
• Question 502:

  The percentage of water of crystallization in ZnSO₄.7H₂O is

  [Zn = 65, S = 32, O = 1, H = 1]

  Options:
  A) 33%
  B) 44%
  C) 55%
  D) 87%
  Show Answer
  The correct answer is B .
• Question 503: Chlorine gas turns a damp starch-iodide paper Options:
  A) pink
  B) colourless
  C) red
  D) dark blue
  Show Answer
  The correct answer is D .
• Question 504: The oxidation number of manganese in KMnO₄ is? Options:
  A) +1
  B) +3
  C) +5
  D) +7
  E) +2
  Show Answer
  The correct answer is D .
• Question 505: Which of the following is used as an 'anti-knock' in automobile engines? Options:
  A) Tetramethyl silane
  B) Lead tetra-ethyl
  C) Glycerol
  D) n-heptane
  Show Answer
  The correct answer is B .
• Question 506:

  Burning magnesium ribbon in air removes which of the following

  (i) oxygen (ii) nitrogen (iii) argon and (iv) carbon(iv)oxide?

  Options:
  A) i and iv only
  B) i, ii, iii and iv only
  C) i only
  D) i and ii only
  Show Answer
  The correct answer is C .
• Question 507:

  Sulphur exists in six forms in the solid state. This property is known as

  Options:
  A) Isomerism
  B) Allotropy
  C) Isotopy
  D) Isomorphism
  Show Answer
  The correct answer is B .
• Question 508: The method that can be used to convert hard water to soft water is Options:
  A) chlorination
  B) passage over activated charcoal
  C) the use of an ion-exchange resin
  D) aeration
  Show Answer
  The correct answer is C .
• Question 509:

  Cr₂O$\frac{2-}{7}$ (aq) + H₂O(1)⇌ 2CrO $\frac{2-}{4}$ (aq) + 2H ⁺ (aq)

  What happens to the reaction above when the hydrogen ion concentration is increased?

  Options:
  A) more of the products will be formed
  B) the reaction will not proceed
  C) the equilibrium position will shift to the right
  D) the equilibrium position will shift to the left.
  Show Answer
  The correct answer is D .
• Question 510: Tartaric acid is used industrially to Options:
  A) make baking powder
  B) make fruit juices
  C) remove rust
  D) dry substance
  Show Answer
  The correct answer is A .