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 681: Which of the following represents the balanced equation for the reaction of copper with concentrated trioxonitrate (V) acid? Options:
  A) Cu _(s) + 2HNO _3(aq) → Cu (NO ₃) _2(aq) + H _2(g)
  B) Cu _(s) + 4HNO _3(aq) → Cu (NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _2(g)
  C) 3Cu _(s) + 8HNO_3(aq) → 3Cu (NO₃)_2(aq) + 4H₂O₍₁₎ + 2NO_(g)
  D) 3Cu_(s) + 4HNO_3(aq) → 3Cu(NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _(g)
  Show Answer
  The correct answer is B .
• Question 682: What is the molar mass of a substance, if 0.4 mole of the substance has a mass of 25.0g? Options:
  A) 62.5 g
  B) 40.0 g
  C) 6.3 g
  D) 2.5 g
  Show Answer
  The correct answer is A .
• Question 683: Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore, Options:
  A) P will form an electrovalent bond with R
  B) Q will form a covalent bond with S
  C) R will form an electrovalent bond with S
  D) Q will form an electrovalent bond with S
  E) Q will form a covalent bond with R
  Show Answer
  The correct answer is D .
• Question 684: An amphoteric oxide is an? Options:
  A) amorphous oxide of a metal
  B) amorphous oxide of a non-mental
  C) oxide that is insoluble in water
  D) oxide that behaves both as a base as well as an acid
  E) oxide that loses its oxygen on sublimation
  Show Answer
  The correct answer is D .
• Question 685:

  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 686: Aluminium is extracted commercially from its ore by? Options:
  A) heating aluminium oxide with coke in a furance
  B) the electrolysis of fused aluminium oxide in cryolite
  C) treating cryolite with sodium hydroxide solution under prressure
  D) heating sodium aluminium silicate to a high temperature
  Show Answer
  The correct answer is B .
• Question 687:

  The equilibrium reaction between copper (l) chloride and chlorine at 25^oC and 1 atmosphere is represented by the equation:

  2CuCl +Cl₂ ⇌ 2 CuCl₂ ∆H = - 166 KJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

  Options:
  A) more CuCl is formed at 40^oC
  B) more CuCl₂ is formed at 10^oC
  C) Less CuCl₂ is formed at 10^oC
  D) there is no change in the amount of CuCl₂ formed at 40^oC and10^oC
  E) more CuCl is consumed at 40^oC
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  The correct answer is B .
• Question 688: An example of a strong electrolyte is? Options:
  A) ethyl acetate
  B) ethanol
  C) glucose
  D) sodium formate
  E) formic acid
  Show Answer
  The correct answer is D .
• Question 689: 2.85g of an oxide of copper gave 2.52g of copper on reduction and 1.90g of another oxide gave 1.52g of copper on reduction. The data above illustrates the law of? Options:
  A) constant composition
  B) conservation of mass
  C) reciprocal proportions
  D) multiple proportions
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  The correct answer is D .
• Question 690: Water is said to be temporarily hard when it contains Options:
  A) Ca (HCO₃)₂ and Mg (HCO₃)₂ salts
  B) Ca (HCO₃)₂ and CaCO₃ SALTS
  C) Mg(HCO₃)₂ and CaSO₄ salts
  D) CaSO₄ and Ca(HCO₃)₂ salts
  Show Answer
  The correct answer is A .