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 171: The oxidation number of manganese in KMnO₄ is? Options:
  A) +1
  B) +3
  C) +5
  D) +7
  E) +2
  Show Answer
  The correct answer is D .
• Question 172: For the reaction 2Fe³⁺ 2I^- $\to$ 2Fe²⁺ + I₂, which of the following statements is TRUE? Options:
  A) Fe is oxidized to Fe³⁺
  B) Fe³⁺ is oxidized to Fe²⁺
  C) I^- is oxidized to I₂
  D) I^- is reduced to I₂
  E) I^- is displacing an electron from Fe³⁺
  Show Answer
  The correct answer is C .
• Question 173:

  A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm³ container at 20°C. The number of moles of gas in the sample is?

  (R = 0.082 litre atm / deg mole)

  Options:
  A) 1.00
  B) 2.00
  C) 3.00
  D) 4.00
  Show Answer
  The correct answer is A .
• Question 174: The component of an atom that contributes least to its mass is the Options:
  A) proton
  B) nucleus
  C) neutron
  D) electron
  Show Answer
  The correct answer is D .
• Question 175:

  Which of the following alkanes has a straight-chain structure?

  Options:
  A) Cyclopentane (C5H10)
  B) Isobutane (C4H10)
  C) 2 - methyl propane (C4H10)
  D) Pentane (C5H12)
  Show Answer
  The correct answer is D .
• Question 176: Which of the following metals is passive to concentrated trioxonitrate (V) acid? Options:
  A) Iron
  B) Tin
  C) Copper
  D) Zinc
  Show Answer
  The correct answer is A .
• Question 177: The conditions necessary for the extraction of a water molecule from two molecules of ethanol are Options:
  A) less acid and lower temperature
  B) excess acid and a lower temperature
  C) excess acid and a higher temperature
  D) less acid and a higher temperature
  Show Answer
  The correct answer is C .
• Question 178:

  Which of the following salts when dissolved in water will NOT give the corresponding pH value?

  Options:
  A) NaHSO₄, pH < 5
  B) Na₂CO₃, pH > 8
  C) Na₂Cl,pH = 7
  D) NaHCO, pH < 6
  Show Answer
  The correct answer is D .
• Question 179: Given the reactions (i) Fe_(s) + X(NO₃)_2(aq) → Fe(NO₃) + X_(s) (ii) H_2(g) + XO _{→ X + H2}O_(s); X is likely to be?
  Options:
  A) copper
  B) zinc
  C) calcium
  D) lead
  Show Answer
  The correct answer is A .
• Question 180: Which of the following happens during the electrolysis of molten sodium chloride? Options:
  A) Sodium ion loses an electron
  B) Chlorine atom gains an electron
  C) Chlorine ion gains an electron
  D) Sodium ion is oxidized
  E) Chloride ion is oxidized
  Show Answer
  The correct answer is E .