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 1931: The general formula of alkanones is Options:
  A) RCHO
  B) R₂CO
  C) RCOOH
  D) RCOOR
  Show Answer
  The correct answer is B .
• Question 1932: In the purification of town water supply, alum is used principally to? Options:
  A) kill bacteria
  B) control the pH of water
  C) improve the taste of the water
  D) coagulate small pasrticles of mud
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  The correct answer is D .
• Question 1933: When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as Options:
  A) disintegration
  B) polymerization
  C) cracking
  D) degradation
  E) distillation
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  The correct answer is C .
• Question 1934: For a general equation of the nature xP + yQ → mR + nS, the expression for the equilibrium constant is Options:
  A) k [P]^x [Q]^y
  B) $\frac{[P{]}^x[Q{]}^y}{[R{]}^m[S{]}^n}$
  C) $\frac{[R{]}^m[S{]}^n}{[P{]}^x[Q{]}^y}$
  D) $\frac{m[R]n[S]}{x[P]y[Q]}$
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  The correct answer is C .
• Question 1935: Water is said to be 'hard' if it Options:
  A) easily forms ice
  B) has to be warmed before sodium chloride dissolves in it
  C) froms an insoluble scum with soap
  D) contains nitrates
  E) contains sodium ions
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  The correct answer is C .
• Question 1936: A white solid suspected to be lead trioxonitrate (V) zinc trioxocarbonate (IV) or calcium trioxocabonate (IV) was heated strongly. Its residue which was yellow when hot and white when cold is? Options:
  A) lead (II) oxide
  B) calcium oxide
  C) zinc oxide
  D) lead nitrate
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  The correct answer is C .
• Question 1937: 0.05 mol dm^-3 HCl is neutralized by 25 cm³ NaOH. If the volume of acid used is 32.00cm³, what is the concentration of the base Options:
  A) 0.016 mol dm^-3
  B) 0.032 mol dm^-3
  C) 0.039 mol dm^-3
  D) 0.064 mol dm^-3
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  The correct answer is D .
• Question 1938: A gas that turns a filter paper previously soaked in lead ethanoate solution black is? Options:
  A) hyrogen chloride
  B) hydrogen sulphide
  C) sulphur (IV) oxide
  D) sulphur (VI) oxide
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  The correct answer is B .
• Question 1939:

  Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

  Options:
  A) Fractional distillation
  B) Filtration followed by distillation
  C) Neutralization with sodium hydroxide followed by distillation
  D) Neutralization with sodium hydroxide followed by filtration
  Show Answer
  The correct answer is B .
• Question 1940:

  If a reaction is exothermic and there is a great disorder, it means that

  Options:
  A) The reaction is in a state of equilibrium.
  B) There will be a large increase in free energy.
  C) There will be a large decrease in free energy.
  D) The reaction is static.
  Show Answer
  The correct answer is C .