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 201: Four elements W, X, Y and Z have atomic number 2,6,16 and 20 respectively. Which of these elements is a metal? Options:
  A) X
  B) W
  C) Z
  D) Y
  Show Answer
  The correct answer is C .
• Question 202:

  What happens to the value of the equilibrium constant (Kc) for a reaction if the reaction is reversed?

  Options:
  A) It becomes zero
  B) It becomes negative
  C) It remains the same
  D) It becomes the reciprocal of the original value
  Show Answer
  The correct answer is D .
• Question 203: Which of the following substances is not a salt? Options:
  A) Aluminium oxide
  B) Sodium hydrogentrioxosulphate (V)
  C) Sodium trioxocarbonate (V)
  D) Zinc chloride
  Show Answer
  The correct answer is A .
• Question 204: The energy value of petrol can be determined by a Options:
  A) bomb calorimeter
  B) catalytic cracker
  C) fractionating column
  D) thermometer
  Show Answer
  The correct answer is C .
• Question 205: Water is said to be 'hard' if it Options:
  A) easily forms ice
  B) has to be warmed before sodium chloride dissolves in it
  C) froms an insoluble scum with soap
  D) contains nitrates
  E) contains sodium ions
  Show Answer
  The correct answer is C .
• Question 206: The constituent common to duralumin and alnico is Options:
  A) Co
  B) Mn
  C) Al
  D) Mg
  Show Answer
  The correct answer is C .
• Question 207: Three solutions contain carbonate, sulphate and sulphide ions respectively. One test that will identify just ONE of them completely is by addition to each of them of Options:
  A) barium chloride solution
  B) dilute hydrochloric acide
  C) lead nitrate solution
  D) calcium chloride solution
  E) sodium hydroxide solution
  Show Answer
  The correct answer is C .
• Question 208: The iron (III) oxide impurity in bauxite can be removed by? Options:
  A) Fractional crystallization in acid solution
  B) dissolution in sodium hydroxide and filtration
  C) extraction with concentrated ammonia and reprecipitation
  D) electroysis of molten mixture
  Show Answer
  The correct answer is B .
• Question 209: The phenomenon whereby sodium trioxocarbonate (IV) decahydrate loses some of its water of crystallization on exposure to the atmosphere is known as? Options:
  A) deliquescene
  B) hygroscopy
  C) effervescence
  D) efflorescence
  Show Answer
  The correct answer is D .
• Question 210: What is the partial pressure of hydrogen gas collected over water at standard atmospheric pressure and 25^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature? Options:
  A) 737 mm Hg
  B) 763 mm Hg
  C) 777 mm Hg
  D) 783 mm Hg
  Show Answer
  The correct answer is A .