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 141: The reddish–brown rust on ion roofing sheets consists of Options:
  A) Fe³ + (H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H2₂O
  Show Answer
  The correct answer is C .
• Question 142:

  In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:

  Anode Cathode

  Options:
  A) Sulphur hydrogen
  B) Hydrogen oxygen
  C) Oxygen Hydrogen
  D) Hydrogen sulphate ions
  E) Sulphur oxygen
  Show Answer
  The correct answer is C .
• Question 143: Which of the following statements is correct about the periodic table? Options:
  A) Elements in the same group have the same number of electron shells
  B) The non-metallic properties of the elements tend to decrease across each period
  C) Elements in the same period have the same number of valence electrons
  D) The valence electrons of the elements increase progressively across the period
  Show Answer
  The correct answer is D .
• Question 144:

  When an acidic solution is diluted, what happens to its pH?

  Options:
  A) It depends on the specific acid
  B) It decreases
  C) It remains the same
  D) It increases
  Show Answer
  The correct answer is D .
• Question 145: CH₃COOC₂H₅(1) + H₂O₍₁₎ ⇌ CH ₃COOH _(aq) + C ₂H ₅OH _(aq)The purpose of H⁺ in the reaction above is to Options:
  A) increase the yield of products
  B) maintain the solution at a constant PH
  C) increase the rate of the hydrolysis
  D) decrease the rate of the reverse reaction
  Show Answer
  The correct answer is A .
• Question 146:

  Which of the following types of bonding does not involve the formation of new substances?

  Options:
  A) Metallic
  B) Covalent
  C) Co-ordinate
  D) Electrovalent
  Show Answer
  The correct answer is A .
• Question 147: The condition required for corrosion to take place is the presence of Options:
  A) water and carbon (IV) oxide
  B) water, carbon (IV) oxide and oxygen
  C) oxygen and carbon (IV) oxide
  D) water and oxygen
  Show Answer
  The correct answer is D .
• Question 148: The property of concentrated H₂SO₄ that makes it suitable for preparing HNO₃ is its Options:
  A) boiling point
  B) density
  C) oxidizing properties
  D) dehydrating properties
  Show Answer
  The correct answer is C .
• Question 149:

  The metal used to recover copper from a solution of copper sulphateis?

  Options:
  A) Na
  B) Ag
  C) Hg
  D) Fe
  Show Answer
  The correct answer is D .
• Question 150:

  An electron can be added to a halogen atom to form a halide ion with?

  Options:
  A) 8 valence electrons
  B) 7 valence electrons
  C) 2 valence electrons
  D) 3 valence electrons
  Show Answer
  The correct answer is A .