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 971: In recharging a lead-acid accumulator, the reaction at the cathode can be represented as Options:
  A) Pb²⁺_(aq) + SO^2-_4(aq) →PbSO_4(s)
  B) Pb²⁺_(aq) + 2e^- →Pb_(s)
  C) Pb²⁺_(aq) + 2H₂O_(l) → PbO_2(s) + 4H⁺_(aq) + 4e^-
  D) Pb_(s) → Pb²⁺_(aq) + 2e^-
  Show Answer
  The correct answer is D .
• Question 972:

  What is the molar mass of water (H2O)?

  Options:
  A) 18 g/mol
  B) 22 g/mol
  C) 16 g/mol
  D) 12 g/mol
  Show Answer
  The correct answer is A .
• Question 973: In order to remove one electron from a 3S orbital of gaseous sodium atom, about 496KJMol^-1 of energy is required. This energy is referred to as Options:
  A) electron affinity
  B) ionization energy
  C) activation evergy
  D) electronegativity
  Show Answer
  The correct answer is B .
• Question 974: The characteristic colour of the flame shown when a copper sail moistened with concentrated hydrochloric acid on a platinum wire is put on bunsen burner is Options:
  A) lilac
  B) green
  C) yellow
  D) brick-red
  Show Answer
  The correct answer is B .
• Question 975:

  CH₃ - CH₂ - C CH

  The hybridization in the compound above is

  Options:
  A) Sp²
  B) sp
  C) sp³ and sp²
  D) sp³ and sp
  Show Answer
  The correct answer is D .
• Question 976:

  2Cl_2(g) + 2H₂O_(g) 4HCl_(g) + O_2(g)

  ∆H° = +115KJ mol^-1. In the above equilibrium reaction, a decrease in temperature will?

  Options:
  A) favour the reverse reaction
  B) favour the forward reaction
  C) have no effect on the equilibrium state
  D) double the rate of the reverse raection
  Show Answer
  The correct answer is A .
• Question 977: Fats and oils are? Options:
  A) addition products of long chain fatty acids and alkali
  B) addition products of long-chain fattyy acids and glycerol
  C) condensation products of long-chain fatty acids and glycerol
  D) condensation products of formaldehyde and glycerol
  E) liquids at 20°C
  Show Answer
  The correct answer is C .
• Question 978: A substance that is used as a ripening agent for fruits is Options:
  A) ethene
  B) propene
  C) methane
  D) butane
  Show Answer
  The correct answer is A .
• Question 979:

  An element has an atomic number of 8 and a mass number of 16. How many neutrons does this element have?

  Options:
  A) 24
  B) 16
  C) 8
  D) 32
  Show Answer
  The correct answer is C .
• Question 980:

  Given that M is the mass of a substance deposited during electrolysis and Q is the quantity of electricity consumed, then Faraday's first law can be written as

  [Electrochemical equivalent]

  Options:
  A) M = E/Q
  B) M = EQ
  C) M = Q/E
  D) M = E/2Q
  Show Answer
  The correct answer is B .