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 1071:

  

  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 .
• Question 1072:

  An isotope has an atomic number of 15 and a mass number of 31. The number of protons it contains is

  Options:
  A) 16
  B) 15
  C) 46
  D) 31
  Show Answer
  The correct answer is B .
• Question 1073: 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
  Show Answer
  The correct answer is C .
• Question 1074:

  What is the main environmental concern associated with sulfur dioxide emissions?

  Options:
  A) Formation of acid rain
  B) Global warming potential
  C) Depletion of the stratospheric ozone
  D) Depletion of the ozone layer
  Show Answer
  The correct answer is A .
• Question 1075: The gas that is used for the treatment of cancer is Options:
  A) Neon
  B) Radon
  C) Xenon
  D) Argon
  Show Answer
  The correct answer is B .
• Question 1076: The mass of silver deposited when a current of 10A is passed through a solution of silver salt for 4830s is – (Ag = 108 F = 96500(mol^-1) Options:
  A) 54.0g
  B) 27.0g
  C) 13.5g
  D) 108.0g
  Show Answer
  The correct answer is A .
• Question 1077: How will a metal X, which reacts explosively with air and with dilute acids be best extracted from its ores? Options:
  A) Electrolysis of solution of its salts
  B) Decomposition of its oxides
  C) Displacement from solution by an alkali metal
  D) Electroiysis of fused salt
  Show Answer
  The correct answer is D .
• Question 1078: Ca(OH)_2(s) + 2NH₄Cl_(g) → CaCl_2(s) + 2H₂O_2(l) + X. In the reaction above X is Options:
  A) NO₂
  B) NH₃
  C) N₂O
  D) NO₂
  Show Answer
  The correct answer is B .
• Question 1079:

  X + Y → Z. The rate equation for the chemical reaction above is ((-Δ[x])/Δt) = K[X]²[Y].

  The overall order of the reaction is

  Options:
  A) 0.0
  B) 1.0
  C) 2.0
  D) 3.09
  Show Answer
  The correct answer is D .
• Question 1080:

  In the preparation of salts, the method employed will depend on the?

  Options:
  A) composition
  B) dissociating ability
  C) stability to heat
  D) precipitating ability
  Show Answer
  The correct answer is C .