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 1081:

  2H₂O _(l) + 2F_2(g) → 4HF_(aq) + O_2(g).

  In the reaction above, the substance that is being reduced is

  Options:
  A) O_2(g)
  B) H₂O_(l)
  C) F_2(g)
  D) HF_(aq)
  Show Answer
  The correct answer is C .
• Question 1082: Which of the following reactions takes place in the cathode compartment during the electrolysis of copper (II) chloride solution? Options:
  A) Cu²⁺ + 2e^- → Cu(s)
  B) 2Cl^- -2e → Cl₂
  C) Cu_(s) -2e → Cu²⁺_(aq)
  D) Cu²⁺_(aq) + 2Cl^-_(aq) → CuCl_2(aq)
  Show Answer
  The correct answer is A .
• Question 1083: When sodium dioxonitrate (lll) (NaNO₂) dissolves in water, ∆H is positive. The process of dissolution is Options:
  A) exothermic
  B) endothermic
  C) isothermal
  D) isomeric
  E) hygroscopic
  Show Answer
  The correct answer is B .
• Question 1084: How many faraday of electricity is required to produce 0.25 mole of copper? Options:
  A) 1.00F
  B) 0.01F
  C) 0.05F
  D) 0.50F
  Show Answer
  The correct answer is D .
• Question 1085: In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl Options:
  A) Cl₂ is reduced because it has lost electrons
  B) Cl₂ is reduced because its oxidation number has decreased
  C) Cl₂ is reduced because its molecule is change to two ions
  D) Fe²⁺ is reduced because it has lost electrons
  E) Fe²⁺ is reduced because it has gained electrons
  Show Answer
  The correct answer is B .
• Question 1086: When sodium is added to ethanol, the products are? Options:
  A) sodium hydroxide and water
  B) sodium hydroxide and hydrogen
  C) sodium ethoxide and water
  D) sodium ethoxide and hydrogen
  Show Answer
  The correct answer is D .
• Question 1087: Alkanals can be distinguished from alkanones by the reaction with Options:
  A) sudan lll stain
  B) starch iodide paper
  C) lithium tetrahydrido aluminate (lll)
  D) fehling's solution
  Show Answer
  The correct answer is D .
• Question 1088:

  An element, X, forms a volatile hydride XH₃ with a vapour density of 17.0. The relative atomic mass of X is?

  (H = 1)

  Options:
  A) 34.0
  B) 31.0
  C) 20.0
  D) 14.0
  Show Answer
  The correct answer is B .
• Question 1089: Which of the following physical properties decreases down a group in the periodic table? Options:
  A) Atomic radius
  B) Ionic radius
  C) Electropositivity
  D) Electronegativity
  Show Answer
  The correct answer is B .
• Question 1090: The entropy and enthalpy of a system are a measure of Options:
  A) degree of disorderlinesss and heat content respectively
  B) heat content and degree of disorderliness respectively
  C) heat content of a system only
  D) degree of disorderliness only
  Show Answer
  The correct answer is A .