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 721: The ability of ionic solids is generally due to the? Options:
  A) negative electron affinity of most atoms
  B) crystal lattice forces
  C) electron pair sharing
  D) positive ionization potentials
  Show Answer
  The correct answer is B .
• Question 722: Which of the following will have its mass increased when heated in air? Options:
  A) Helium
  B) Magnesium
  C) Copper pyrites
  D) Glass
  Show Answer
  The correct answer is B .
• Question 723:

  Which of the following gases will rekindle a brightly splint?

  Options:
  A) NO${}_2$
  B) NO
  C) N${}_2$O
  D) CL${}_2$
  Show Answer
  The correct answer is C .
• Question 724: In the course of an experiment, two gases X and Y were produced. X turned wet lead ethanoate to black and Y bleached moist litmus paper. What are the element(s) in each of the gases X and Y respectively? Options:
  A) H and S;Cl
  B) H and O;Cl
  C) H and S;C and O
  D) H and Cl;S and O
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  The correct answer is A .
• Question 725:

  What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?

  Options:
  A) 24,125 C
  B) 48,250 C
  C) 72,375 C
  D) 96,500 C
  Show Answer
  The correct answer is B .
• Question 726:

  Which of the following is a form of calcium carbonate?

  I. limestone
  II. marble
  III. chalk
  Iv. egg-shells

  Options:
  A) I only
  B) I, II and IV
  C) I and II only
  D) I, II, III, and IV
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  The correct answer is D .
• Question 727:

  Methane is prepared in the laboratory by heating a mixture of sodium ethanoate with soda lime. The chemical constituent(s) of soda lime is/are

  Options:
  A) Ca(OH)${}_2$ and NaOH
  B) Na${}_2$CO${}_3$
  C) NaCl
  D) NaOH
  Show Answer
  The correct answer is A .
• Question 728: The number of atoms in one mole of a substance is equal to? Options:
  A) the atomic number
  B) the avogadro number
  C) the gas constant
  D) the number of neutrons
  E) the number of electrons
  Show Answer
  The correct answer is B .
• Question 729: Aromatic and aliphatic hydrocarbons can be distinguished from each other by the? Options:
  A) action of bromine
  B) use of polymerization reaction
  C) action of heat
  D) use of oxidation reaction
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  The correct answer is C .
• Question 730: When carbondioxide is bubbled into limewater a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is Options:
  A) calcium carbonate is formed which on reaction dissolves
  B) calcium hydrogen carbonate is precipitated and then dissolves
  C) calcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate
  D) concentration of the solution has occurred with the deposition of calcium hydroxide
  E) the solution has become saturated and solid carbondioxide has been deposited
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  The correct answer is C .