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 1771: The reddish-brown rust on iron roofing sheets consists of Options:
  A) Fe³⁺(H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H₂O
  Show Answer
  The correct answer is C .
• Question 1772: A catalyst speeds up the rate of chemical reaction by Options:
  A) taking part in the reaction
  B) increasing the activation energy of the reaction
  C) lowering the activation energy of the reaction
  D) increasing the heat content
  Show Answer
  The correct answer is C .
• Question 1773:

  2H₂S_(g) + SO_2(g) + H₂O_(l) → 3S_(s) + 3H₂O_(l)..........(I)

  3CuO_(s) + 2NH_3(g) → 3Cu_(s) + 3H₂O_(l) + N_2(g).........(II)

  In the equations above, the oxidizing agent (I) and the reducing agent in (II) respectively are?

  Options:
  A) H₂S and NH₃
  B) SO₂ and CuO
  C) SO₂ and NH₃
  D) H₂S and CuO
  Show Answer
  The correct answer is C .
• Question 1774: The active reducing agent in the blast furnace for the extraction of iron is? Options:
  A) carbon
  B) limestone
  C) carbon(II)oxide
  D) calcium oxide
  Show Answer
  The correct answer is C .
• Question 1775: The acid in electrolysis of water is dilute Options:
  A) HNO₃
  B) CH₃COOH
  C) H₂SO
  D) HCl
  Show Answer
  The correct answer is C .
• Question 1776: Due to the unstable nature of ethyne, it is stored by dissolving in Options:
  A) ethane-1,2-diol
  B) propanol
  C) ethanoic acid
  D) propanone
  Show Answer
  The correct answer is D .
• Question 1777: An endothermic reaction is one during which heat is.....and can be represented by the symbol.... which of the following combinations can be used accurately to complete the above definition? Options:
  A) liberated, -$\mathrm{\Delta }$H
  B) liberated, +$\mathrm{\Delta }$H
  C) absorbed, -$\mathrm{\Delta }$H
  D) absorbed, +$\mathrm{\Delta }$H
  E) absorbed, +$\mathrm{\Delta }$G
  Show Answer
  The correct answer is D .
• Question 1778: The main impurity in iron ore during the extraction of iron is Options:
  A) Silicon (IV) oxide
  B) Carbon (IV) oxide
  C) Calcium trioxosilicate
  D) Sulphur (II) oxide
  Show Answer
  The correct answer is A .
• Question 1779: Which of the following class of compounds can exist as dipolar ions in solution? Options:
  A) Alkanoic acid
  B) Fatty acids
  C) Dialkanoic acids
  D) Amino acids
  Show Answer
  The correct answer is D .
• Question 1780: Which of the following acts as both a reducing and an oxidizing agent? Options:
  A) H₂
  B) SO₂
  C) H₂S
  D) C
  Show Answer
  The correct answer is B .