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 21:

  

  The diagram above is the solubility curve of a solute, X. Find the amount of X deposited when 500cm³ of a solution of X is cooled from 60^oC to 20^oC.

  Options:
  A) 0.750 mole
  B) 0.950 mole
  C) 2.375 moles
  D) 4.750 moles
  Show Answer
  The correct answer is A .
• Question 22: The reddish–brown rust on ion roofing sheets consists of Options:
  A) Fe³ + (H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H2₂O
  Show Answer
  The correct answer is C .
• Question 23:

  

  The functional group represented in the compound above is

  Options:
  A) alkanol
  B) alanal
  C) alkanone
  D) alanoate
  Show Answer
  The correct answer is C .
• Question 24: For the reaction 2Fe³⁺ 2I^- $\to$ 2Fe²⁺ + I₂, which of the following statements is TRUE? Options:
  A) Fe is oxidized to Fe³⁺
  B) Fe³⁺ is oxidized to Fe²⁺
  C) I^- is oxidized to I₂
  D) I^- is reduced to I₂
  E) I^- is displacing an electron from Fe³⁺
  Show Answer
  The correct answer is C .
• Question 25:

  

  The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is

  Options:
  A) 0.2 moles
  B) 0.7 moles
  C) 1.5 moles
  D) 2.0 moles
  E) 3.0 moles
  Show Answer
  The correct answer is B .
• Question 26: Chlorination of water for town supply is carried out to Options:
  A) make the water colourless
  B) remove germs from the water
  C) make the water tastedful
  D) remove odour from the water
  Show Answer
  The correct answer is B .
• Question 27:

  The end products of burning a candle in the atmosphere are water and 

  Options:
  A) carbon (II) oxide
  B) sulphur (IV) oxide
  C) carbon (IV) oxide
  D) sulphur (VI) oxide
  Show Answer
  The correct answer is C .
• Question 28:

  Which of the following is an example of a chemical change?

  Options:
  A) dissolution of salt in water
  B) rusting of iron
  C) melting of ice
  D) separating a mixture by distillation
  Show Answer
  The correct answer is B .
• Question 29: What properties of duralumin make it more useful than its constituent metals? Options:
  A) It is heavy with a high melting point
  B) It is malleable and has high density
  C) It is strong and light
  D) It is hard and ductile
  Show Answer
  The correct answer is C .
• Question 30:

  

  The diagram above shows the reaction path of an exothermic reaction. The heat of reaction is represented by

  Options:
  A) l
  B) ll
  C) lll
  D) lV
  Show Answer
  The correct answer is D .