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 991: The principle of column chromatography is based on the ability of the constituents to Options:
  A) move at different speeds in the column
  B) dissolve in each other in the column
  C) react with the solvent in the column
  D) react with each other in the column
  Show Answer
  The correct answer is A .
• Question 992: The number of hydroxonium ions produced by one molecule of an acid in aqueous solution is its Options:
  A) basicity
  B) acid strength
  C) pH
  D) concentration
  Show Answer
  The correct answer is B .
• Question 993: Which of the following metals will liberate hydrogen from steam or dilute acid? Options:
  A) Copper
  B) Iron
  C) Lead
  D) Mercury
  Show Answer
  The correct answer is B .
• Question 994: 5 block elements of the periodic table one made up of Options:
  A) groups 1, 2, 3
  B) groups 1, and 2
  C) group 3
  D) group 3 to 7
  Show Answer
  The correct answer is B .
• Question 995:

  A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.

  [H = 1, C = 12, O = 16]

  Options:
  A) C${}_3$H${}_6$O${}_3$
  B) C${}_6$H${}_6$O${}_3$
  C) C${}_6$H${}_{12}$O${}_6$
  D) CH${}_2$O
  Show Answer
  The correct answer is C .
• Question 996: Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises? Options:
  A) The bonds in the reacting molecules are more readily broken
  B) The molecular collisions become more violent
  C) A lower proportion of the molecules has the necessary minimum energy to react
  D) The collision frequency of the molecules increase
  Show Answer
  The correct answer is D .
• Question 997: An organic compound contains 60% carbon, 13.3% hydrogen and 26.7% oxygen. Calculate the empirical formula
  rn(C=12,H =1, O=16) Options:
  A) C ₅H ₁₂O
  B) C ₃H ₈O
  C) C ₆H ₁₃O ₂
  D) C ₄H ₉O
  Show Answer
  The correct answer is B .
• Question 998:

  Which of the following represents the kind of bonding present in ammonium chloride?

  Options:
  A) ionic only
  B) covalent only
  C) ionic and dative covalent
  D) dative covalent
  Show Answer
  The correct answer is C .
• Question 999: A chemical reaction which the hydration energy is greater than the lattice energy is referred to as Options:
  A) a spontaneous reaction
  B) an endothermic reaction
  C) an exothermic reaction
  D) a reversible reaction
  Show Answer
  The correct answer is C .
• Question 1000: The nitrogen gas obtained by burning an excess of phosphorus in air has a density higher than the nitrogen from nitrogen compounds because the nitrogen from air is contaminated with? Options:
  A) some unburnt phosporus
  B) P₂O₅ vapour
  C) some oxygen
  D) rare gases
  E) carbondioxide
  Show Answer
  The correct answer is D .