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 1671:

  Two cylinders A and B each contains 30 cm³ of

  Oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?

  Options:
  A) 3.2 g
  B) 6.4 g
  C) 80.0 g
  D) 160.0 g
  Show Answer
  The correct answer is D .
• Question 1672:

  Which of the following can be obtained by fractional distillation? 

  Options:
  A) Nitrogen from liquid air
  B) Sodium Chloride from sea water
  C) Iodine from solution of Iodine in carbon tetrachloride
  D) Sulphur from the solution of sulphur in carbon disulphide
  Show Answer
  The correct answer is A .
• Question 1673:

  An organic compound has an empirical formula CH₂O and vapour density of 45.

  What is the molecular formula?

  [C = 12, H = 1, O = 16]

  Options:
  A) C₃H₇OH
  B) C₂H₅OH
  C) C₃H₆O₃
  D) C₂H₄O₂
  Show Answer
  The correct answer is C .
• Question 1674:

  

  In the diagram above, which of the curves represents the evolution of oxygen with time in the equation 2KClO_3(s) → 2KCl_(s) + 3O_2(g)?

  Options:
  A) X
  B) Y
  C) Z
  D) R
  Show Answer
  The correct answer is C .
• Question 1675:

  What is the atomic number of aluminium?

  Options:
  A) 13
  B) 26
  C) 14
  D) 12
  Show Answer
  The correct answer is A .
• Question 1676:

  

  The diagram above shows the reaction path of an exothermic reaction. The heat of reaction is represented by

  Options:
  A) l
  B) ll
  C) lll
  D) lV
  Show Answer
  The correct answer is D .
• Question 1677:

  What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours, through molten magnesium chloride?
  [1 faraday = 96500C, Mg = 24]

  Options:
  A) 1.12g
  B) 4.48g
  C) 1.80g
  D) 2.00g
  Show Answer
  The correct answer is C .
• Question 1678: S₂O^2-₃ + I₂ → S₂O₆^2- + 2I^-. In reaction above, the oxidizing agent is? Options:
  A) S₂O₃^2-
  B) I₂
  C) S₄O₆^2-
  D) I^-
  Show Answer
  The correct answer is B .
• Question 1679:

  Which of the following is a common property of non-metals?

  Options:
  A) Exist as solids at room temperature
  B) Tend to gain electrons in chemical reactions
  C) High thermal conductivity
  D) Readily form cations in chemical reactions
  Show Answer
  The correct answer is B .
• Question 1680:

  I. It has a varied composition from one place to another.

  II. It constituents can be separated by physical means.

  III. It contains unreactive noble gases

  Which of the above shows that air is a mixture?

  Options:
  A) I and II only
  B) II and III only
  C) I and III only
  D) I, II and III
  Show Answer
  The correct answer is A .