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 111:

  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 .
• Question 112:

  3H${}_{2(g)}$+ N2 ⇔ 2NH${}_{3(g)}$ ; H= -ve

  In the reaction above, lowering of temperature will

  Options:
  A) have no effect on the equilibrium position
  B) increase the rate of both the forward and reverse reactions equally
  C) favour the forward reaction
  D) favour the reverse reaction
  Show Answer
  The correct answer is C .
• Question 113: Coffee stains can best be removed by Options:
  A) Kerosine
  B) turpentine
  C) a solution of borax in water
  D) ammonia solution
  Show Answer
  The correct answer is C .
• Question 114: Which of the following decrease when a given mass of gas is compressed to half its initial volume? Options:
  A) Atomic radius of each
  B) Average intermolecular distance
  C) Frequency of collisions
  D) Number of molecules presents
  Show Answer
  The correct answer is B .
• Question 115:

  Which of the gas laws does this graph illustrate?

  Options:
  A) Boyle
  B) Charles
  C) Gay-Lussac
  D) Graham
  Show Answer
  The correct answer is B .
• Question 116:

  The maximum electron in N shell is?

  Options:
  A) 2
  B) 8
  C) 18
  D) 32
  Show Answer
  The correct answer is D .
• Question 117: Chlorine gas turns a damp starch-iodide paper Options:
  A) pink
  B) colourless
  C) red
  D) dark blue
  Show Answer
  The correct answer is D .
• Question 118:

  Which of the following gases can best be used for demonstrating the fountain experiment?

  (iv) Hydrogen chloride.

  Options:
  A) ii and iii
  B) i and iii
  C) ii and iv
  D) ii only
  E) Nitrogen (ii) Ammonia (iii) Nitrogen (I) oxide
  Show Answer
  The correct answer is C .
• Question 119:

  A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as __________.

  Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 120: The shape of the carbon (lV) oxide molecule is Options:
  A) pyramidal
  B) linear
  C) angular
  D) tetrahedral
  Show Answer
  The correct answer is B .