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: A hydrated salt of formula MSO₄.xH₂ O CONTAINS 45.3% by mass of water of crystalisation. Calculate the value of x [M = 56, S = 32, O = 16, H = 1 ] Options:
  A) 3
  B) 5
  C) 7
  D) 10
  Show Answer
  The correct answer is C .
• Question 32: Calcium tetraoxosulphate (VI) dissolves in water only sparingly to form a Options:
  A) solution
  B) suspension
  C) precipitate
  D) colloid
  Show Answer
  The correct answer is C .
• Question 33: 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 34: N₂O_4(g)→ 2NO_2(g)In the endothermic reaction above, more products formed will be favored by Options:
  A) A constant values
  B) an increase in pressure
  C) a decrease pressure
  D) a decrease volume
  Show Answer
  The correct answer is C .
• Question 35: In which of the following are water molecules in the most disorderly arrangement? Options:
  A) Ice at -10°C
  B) Ice at 0°C
  C) Water at 100°C
  D) Steam at 100°C
  Show Answer
  The correct answer is D .
• Question 36:

  What is the main source of carbon monoxide (CO) in urban areas?

  Options:
  A) Volcanic eruptions
  B) Vehicle emissions
  C) Forest fires
  D) Industrial processes
  Show Answer
  The correct answer is B .
• Question 37:

  Temp (°C)	25	35	45
  Time (seconds)	72	36	18

  The times taken for iodine to be liberated in the reaction between sodium thiosulphate and hydrochloric acid at various temperature are as follows. These results suggest that

  Options:
  A) for a 10^o rise in temperature, rate of reaction is double
  B) for a 10 ^o rise in temperature, rate of reaction is halved
  C) time taken for iodine to appear does not depend on temperature
  D) for a 10 ^o rise in temperature rate of reaction is tripled
  Show Answer
  The correct answer is A .
• Question 38: Mineral acids are usually added to commercial hydrogen peroxide to Options:
  A) oxidize it
  B) decompose it
  C) minimize its decomposition
  D) reduce it to water and oxygen
  Show Answer
  The correct answer is C .
• Question 39:

  

  In the diagram above, mixture Y is

  Options:
  A) NH₄NO_3(s) + CaSO_4(s),/sub>
  B) NH₄CL_(s) + NaNO_2(s)
  C) NH₄NO_2(s) + Na₂SO_4(s)
  D) NH₄CL_(s) + Ca(OH)_2(s)
  Show Answer
  The correct answer is D .
• Question 40:

  Al₂O_3(s) + 3H₂SO_4(aq) → Al₂(SO_4(aq)) + 3H_2(I)O

  Al₂O_3(s) + 2NaOH_(aq)) + 3H_2(I)O → 2NaAl(OH)_4(aq)).

  We can conclude from the equations above that Al₂O_3(s) is?

  Options:
  A) an acidic oxide
  B) an amphoteric oxide
  C) a basic oxide
  D) a neutral oxide
  Show Answer
  The correct answer is B .