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 1911: 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 1912:

  CO_(g) + H₂ O_(g) → CO_2(g) + H_2(g)

  Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) and CO_(g) in KJ mol ^-1 are - 394 -242 and - 110 respectively.

  Options:
  A) + 262 KJ mol ^-1
  B) - 262 KJ mol ^-1
  C) + 42 KJ mol ^-1
  D) - 42 KJ mol ^-1
  Show Answer
  The correct answer is D .
• Question 1913: In the laboratory preparation of ethyl ethanoate, the water present in the mixture is removed using a solution of Options:
  A) an hydrous CaCl₄
  B) concentrated NaCO₄
  C) dilute NaOH
  D) concentrated H₄SO₄
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  The correct answer is D .
• Question 1914: A few drops of concentrated PCI are added to about 10cm³ of a solution of pH 3.4. The pH of the resulting mixtures is? Options:
  A) less than 3.4
  B) greater than 3.4
  C) unaltered
  D) the same as that of pure water
  Show Answer
  The correct answer is C .
• Question 1915:

  Which of the following does not support the fact that air is a mixture?

  Options:
  A) the constituents of air are in a fixed proportion by mass
  B) it cannot be represented with a chemical formula
  C) the constituents of air can be separated by physical by physical means
  D) none of the above
  Show Answer
  The correct answer is A .
• Question 1916: The combustion of ethene, C ₂H ₄, is given by the equation C ₂H ₄ + 30 ₂ → 2CO₂ + 2H₂ O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ Options:
  A) - 2792
  B) + 2792
  C) - 64
  D) + 64
  Show Answer
  The correct answer is D .
• Question 1917: Using 50 cm ³ of 1 M potassium hydroxide and 100cm ³ of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm ³ of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [ = 39, S = 32, O = 16, H = 1] Options:
  A) 50, 50
  B) 25, 50
  C) 50, 25
  D) 25, 25
  Show Answer
  The correct answer is D .
• Question 1918: 2CL^-_(aq) → CI_2(g) + 2e^-(aq). The above half-cell reaction occuring at the anode during the electrolysis of dilute ZnCI₂ solution is? Options:
  A) ionization
  B) oxidation
  C) reduction
  D) recombination
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  The correct answer is B .
• Question 1919: The ability of carbon to form long chains is referred to as Options:
  A) Alkylation
  B) Acylation
  C) Carbonation
  D) Catenation
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  The correct answer is D .
• Question 1920: Which of the following molecules has two other positional isomers? Options:
  A) CH₃CH₂Br
  B) CH₃CHBrCH₃
  C) CBr₂F₂
  D) CH₂CHBrCH₂Br
  Show Answer
  The correct answer is D .