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 191: In an attempt to remove sugar from a breaker containing a quantity of sand and sugar, 2 M ammonium chloride solution was accidentally added instead of water. Which of the following method could be used to remove the ammonium chloride from the mixture? Options:
  A) Fractional distillation
  B) crystallization
  C) Filtration followed by evaporation
  D) Evaporation followed by sublimation
  E) Filtration followed by sublimation
  Show Answer
  The correct answer is D .
• Question 192:

  The presence of ammonia gas in a desiccator can exclusively be removed by

  Options:
  A) phosphorus (V) oxide
  B) fused calcium chloride
  C) calcium chloride
  D) concentrated tetraoxosulphate (VI) acid
  Show Answer
  The correct answer is D .
• Question 193: The gasification of coke is used for the manufacturing of Options:
  A) producer gas
  B) natural gas
  C) synthetic gas
  D) industrial gas
  Show Answer
  The correct answer is C .
• Question 194: Water molecules can be liquids especially when they are bonded to Options:
  A) alkaline earth metals
  B) alkali metals
  C) transition metals
  D) group VII elements
  Show Answer
  The correct answer is C .
• Question 195: The reaction that takes place in Daniell cell is Options:
  A) direct combination
  B) redox
  C) double decomposition
  D) neutralization
  Show Answer
  The correct answer is B .
• Question 196: In an endothermic reaction, if there is a loss in entropy the reaction will Options:
  A) be indeterminate
  B) be spontaneous
  C) not be spontaneous
  D) be at equilibrium
  Show Answer
  The correct answer is C .
• Question 197: Which of the following combinations of conditions may increase the rate of a chemical reaction? Options:
  A) Decrease in temperature, increase in concentration of the reactants
  B) Increase in temperature, addition of a catalyst, decrease in the surface area of the reactants
  C) Increase in temperature, increase in concentration, addition of a catalyst and increase in the surface area of the reactants
  D) Decrease in temperature concentration and surface area of the reactants
  E) Additionof a catalyst and in the absence of light
  Show Answer
  The correct answer is C .
• Question 198: Iron is often galvanized in order to Options:
  A) Make it more malleable
  B) Remove the impurities unit
  C) Protect it against corrosion
  D) Render it passive
  Show Answer
  The correct answer is C .
• Question 199:

  An element has an atomic number of 8 and a mass number of 16. How many neutrons does this element have?

  Options:
  A) 24
  B) 16
  C) 8
  D) 32
  Show Answer
  The correct answer is C .
• Question 200:

  

  In the diagram above, Y is a mixture of

  Options:
  A) calcium hydroxide and ammonium chloride
  B) calcuim hydroxide and sodium chloride
  C) sodium chloride and ammonuim trioxonitrate (V)
  D) sodium dioxonitrate (lll) and ammouium chloride
  Show Answer
  The correct answer is A .