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 21:

  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 22:

  What are the possible oxidation numbers of an element if its atomic number is 17?

  Options:
  A) -1 and 7
  B) -1 and 6
  C) -3 and 5
  D) -2 and 6
  Show Answer
  The correct answer is A .
• Question 23: Three drops of a 1.0 mol dm^-3 solution of HCl was added to 20 cm³ of a solution of pH6.4. The pH of the resulting solution will be Options:
  A) close to that of pure water
  B) less than 6.4
  C) greater than 6.4
  D) unaltered
  Show Answer
  The correct answer is B .
• Question 24: The pollution from petroleum spillage in rivers and lakes can best be dispersed by Options:
  A) Pouring detergents
  B) Passing of ships through the area
  C) Pouring organic solvents
  D) Evaporation
  Show Answer
  The correct answer is A .
• Question 25: The electron configuration of two elements with similar chemical properties are represented by? Options:
  A) 1s²2s²2p⁵ and 1s²2s²2p⁴
  B) 1s²2s²2p⁴ and 1s²2s²2p⁶3s¹
  C) 1s²2s²2p⁶3s¹ and 1s²2s¹
  D) 1s²2s²2p⁴ and 1s²2s¹
  Show Answer
  The correct answer is C .
• Question 26:

  The only metal that is anti-bacterial is?

  Options:
  A) Iron
  B) Sodium
  C) Alluminium
  D) Copper
  Show Answer
  The correct answer is D .
• Question 27: When a piece of charcoal enclosed in a cylinder containing air is ignited Options:
  A) the toatl volume of air is increased
  B) the relative amount of oxygen present is increased
  C) the relative amount of nitrogen present is decreased
  D) the relative amount of carbondioxide present is increased
  E) the ratio of oxygen to nitrogen in the system is increased
  Show Answer
  The correct answer is D .
• Question 28: The solubility curve shows the variation of solute concentration with Options:
  A) volume
  B) temperature
  C) vapour density
  D) pressure
  Show Answer
  The correct answer is B .
• Question 29: A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, Find the molecular formula [H = 1, C = 12, O = 16) Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₁₂O₆
  D) C₆H₁₂O₃
  Show Answer
  The correct answer is C .
• Question 30: A compound contains 40.0% C, 6.7% H 53.3% O. If the molecular mass of the compound is 180, its molecular formula is [C =12, H =1,O] Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₆O₃
  D) C₆H₁₂O₆
  Show Answer
  The correct answer is D .