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 941: The enzymes responsible for converting sucrose into two simple isomeric sugars is Options:
  A) maltase
  B) amylase
  C) invertase
  D) lactase
  Show Answer
  The correct answer is C .
• Question 942: The oxidation number of manganese in KMnO₄ is? Options:
  A) +1
  B) +3
  C) +5
  D) +7
  E) +2
  Show Answer
  The correct answer is D .
• Question 943: A difference between chemical and physical change is that in a chemical change Options:
  A) oxygen is consumed
  B) heat is supplied
  C) a reversible process oocurs
  D) a new substance is formed
  Show Answer
  The correct answer is D .
• Question 944:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100^oC, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0^oC?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 945: The nitrogen obtained from air has a density higher than the one from nitrogen-containing compounds because the one from air is contaminated with Options:
  A) water vapour
  B) oxgyen
  C) rare gases
  D) carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 946: Which of the following is used as fuel in miners' lamp? Options:
  A) Ethanal
  B) Ethyne
  C) Ethene
  D) Ethane
  Show Answer
  The correct answer is B .
• Question 947: A good drying agent should be Options:
  A) deliquescent
  B) effervescent
  C) hygroscopic
  D) efflorescent
  Show Answer
  The correct answer is C .
• Question 948: The structural component that makes detergent dissolve more quickly in water than soap is Options:
  A) -SO₃- Na⁺
  B) -COO-Na^-
  C) -SO₄- Na⁺
  D) -COO-K⁺
  Show Answer
  The correct answer is A .
• Question 949: The knowledge of half-life can be used to Options:
  A) create an element
  B) detect an element
  C) split an element
  D) irradiate an element
  Show Answer
  The correct answer is A .
• Question 950: A solution containing chloride ions gives white precipitate with silver trioxonitrate(V) Solution. The precipitate will be insoluble in dilute? Options:
  A) HNO ₃ but soluble in ammonia solution
  B) HNO₃ and ammonia solution
  C) HCl but soluble in ammonia solution
  D) HCl and in ammonia solution
  Show Answer
  The correct answer is A .