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 481: Which of the following equilibria shows little or no net reaction when the volume of the system is decreased? Options:
  A) H_2(g) + I_2(g) ≈ 2HI_(g)
  B) 2NO₂^(g) ≈ N₂O_4(g)O_4(g)N₂O_4(g)
  C) PCI_5(g) ≈ PCI_3(g) + CI_2(g)
  D) ZnO_(s) + CO_2(g) ≈ ZnCO_3(g)
  Show Answer
  The correct answer is D .
• Question 482:

  The reactions involving simultaneous oxidation and reduction?

  Options:
  A) Automatic reactions
  B) Alternate reactions
  C) Reduction agency
  D) Redox reactions
  Show Answer
  The correct answer is D .
• Question 483: The rate of diffusion of a gas Y is twice that of Z If the relative molecular mass of Y is 64 and the two gases diffuse under the same conditions, find the relative molecular mass of Z Options:
  A) 32
  B) 4
  C) 8
  D) 16
  Show Answer
  The correct answer is D .
• Question 484: A few drops of NaOH solution was added to an unknown salt forming a white precipitate which is insoluble in excess solution. The cation likely present is Options:
  A) Zn²⁺
  B) Pb²⁺
  C) Ca²⁺
  D) Al³⁺
  Show Answer
  The correct answer is C .
• Question 485: Which of the following reactions is correct as as written? Options:
  A) FeCl₂ + 3NH₄OH → Fe(OH)₃ + 3NH₄Cl
  B) Pb₂O₃ + 4HCl → PbCl₂ + 2H₂O
  C) PbNO₃ + H₂S → PbS + 2HNO₃
  D) NaOH + H₂SO₄ → NaHSO₄ +H₂O
  E) 2NH₄NO₃ → N₂ + 2H₂O
  Show Answer
  The correct answer is D .
• Question 486: Sieving is a technique used to separate mixture containing solid particles of Options:
  A) small sizes
  B) large sizes
  C) differents sizes
  D) the same sizes
  Show Answer
  The correct answer is C .
• Question 487:

  Which of the following methods is commonly used to remove suspended impurities from water?

  Options:
  A) Fluoridation
  B) Chlorination
  C) Filtration
  D) Distillation
  Show Answer
  The correct answer is C .
• Question 488: 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 489: What is the consequences of increasing pressure on the equilibrium reaction ZnO_(s) + H_2(g) Zn_(s) + H₂O_(I)? Options:
  A) The equilibrium is driven to the left
  B) The equilibrium is driven to the right
  C) There is no effect
  D) More ZnO is produced
  Show Answer
  The correct answer is C .
• Question 490: How much of magnesium is required to react with 260cm³ of 0.5 M HCl? [Mg = 24] Options:
  A) 0.3g
  B) 1.5g
  C) 2.4g
  D) 3.0g
  Show Answer
  The correct answer is B .