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 31: To make coloured glasses, small quantities of oxides of metals which form coloured silicates are often added to the reaction mixture consisting of Na₂CO₃ and SiO₂. Such a metals is a?. Options:
  A) pottasium
  B) barium
  C) zinc
  D) copper
  Show Answer
  The correct answer is D .
• Question 32:

  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 .
• Question 33:

  

  Use the above option to answer this question. The dehydration of ammonium salt of alkanoic acids produces a compound with the general formula

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 34: The oxidation state of manganese in potassium permanganate is Options:
  A) +7
  B) +5
  C) +3
  D) +2
  E) +1
  Show Answer
  The correct answer is A .
• Question 35: When ΔH is negative, a reaction is said to be Options:
  A) ionic
  B) reversible
  C) exothermic
  D) endothermic
  Show Answer
  The correct answer is C .
• Question 36: The element with the electron configuration 1s²2s²2p³ is Options:
  A) calcium
  B) chlorine
  C) oxygen
  D) nitrogen
  Show Answer
  The correct answer is D .
• Question 37: Copper (II) tetraoxosulphate (IV) is widely used as a? Options:
  A) fertilizer
  B) fungicide
  C) disinfectant
  D) purifier
  Show Answer
  The correct answer is B .
• Question 38:

  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 .
• Question 39: A silicon -containing ore has 92% ²⁸Si, 5% ²⁹Si and 3% ³⁰Si. Calculate the relative atomic mass of the silicon. Options:
  A) 14.00
  B) 29.00
  C) 28.11
  D) 28.00
  Show Answer
  The correct answer is C .
• Question 40: The flame used by welders in cutting metals is Options:
  A) butane gas flame
  B) acetylene flame
  C) kerosene flame
  D) oxy-acetylene flame
  E) oxygen flame
  Show Answer
  The correct answer is D .