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 151: Given that the molecular mass of iron is 56 and that of oxygen is 16, how many moles of iron(iii)oxide will be contained in 1kg of the compound? Options:
  A) 25.0 moles
  B) 12.5 moless
  C) 6.25 moles
  D) 3.125 moles
  E) 0.625 moles
  Show Answer
  The correct answer is C .
• Question 152:

  A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].

  Options:
  A) 2.7g
  B) 1.2g
  C) 0.9g
  D) 0.3g
  Show Answer
  The correct answer is A .
• Question 153:

  Cu²⁺_(aq) + 4NH_3(g) ↔ [Cu(NH₃)₄]²⁺_(aq)

  In the reaction above, what is the effect of precipitating Cu²⁺_(aq) as CuS_(s)?

  Options:
  A) NH_3(g) concentration will decrease
  B) more NH_3(g)
  C) The equilibrium will shift to the right
  D) There will be no effect
  Show Answer
  The correct answer is C .
• Question 154:

  200 cm³ of air was passed over heated copper in a syringe several times to produce copper (II) oxide.

  When cooled, the final volume of air recorded was 158cm³. Estimate the percentage of oxygen in the air?

  Options:
  A) 31%
  B) 27%
  C) 21%
  D) 19%
  Show Answer
  The correct answer is C .
• Question 155: In dilute solution the heat of the reaction NaOH + HCl = NaCl + H2O is - 57.3kJ. Therefore the heat of the reaction 2NaOH + H₂SO₄ $\to$ Na₂SO₄ + 2H₂O is Options:
  A) + 28.65 kJ
  B) - 28.65KJ
  C) + 57.3KJ
  D) - 114.6 KJ
  E) - 229.2 KJ
  Show Answer
  The correct answer is D .
• Question 156: Which of the following is a solvent for perfumes? Options:
  A) C₅H₁₂
  B) C₄H₆
  C) CH₃COOH
  D) C₂H₅OH
  Show Answer
  The correct answer is D .
• Question 157:

  The sulphide that is commonly used in coating electric fluorescent tubes is?

  Options:
  A) iron(ii)Sulphide
  B) tin(ii)sulphide
  C) Zinc Sulphide
  D) lead(iv) Sulphide
  Show Answer
  The correct answer is C .
• Question 158: 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
  Show Answer
  The correct answer is D .
• Question 159:

  Which halogen is a gas at room temperature and is pale yellow in color?

  Options:
  A) Chlorine (Cl)
  B) Fluorine (F)
  C) Iodine (I)
  D) Bromine (Br)
  Show Answer
  The correct answer is B .
• Question 160: A red precipitate of copper (I) carbide is formed when ammonium solution of copper (I) chloride is introduced into Options:
  A) CH₃CH₂CH₂CH₃
  B) CH₂ = CH - CH₂CH₃
  C) CH₃CH₂ - C = CH
  D) CH₃ - C = C - CH₃
  Show Answer
  The correct answer is C .