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 241: 20.00 cm ³ of a solution containing 0.53 g of anhydrous Na₂CO₃ in 100 cm³ requires 25.00 cm³ of H₂SO₄ for complete neutralisation. The concentration of the acid solution in moles per dm is [H =1, C = 12, O = 16, Na =23, S = 32] Options:
  A) 0.02
  B) 0.04
  C) 0.06
  D) 0.08
  Show Answer
  The correct answer is B .
• Question 242: The process of converting starch to ethanol is Options:
  A) cracking
  B) distillation
  C) fermentation
  D) oxidation
  Show Answer
  The correct answer is C .
• Question 243:

  The molecular shape and bond angle of water are respectively

  Options:
  A) linear, 180°
  B) bent, 109.5°
  C) tetrahedral, 109.5°
  D) bent, 105°
  Show Answer
  The correct answer is D .
• Question 244:

  Which process(es) is/are involved in the turning of starch iodide paper blue-black by chlorine gas?

  Options:
  A) chlorine attacks the starch to give the blue-black color
  B) chlorine attacks the iodide ion to give the blue-black color
  C) chlorine oxidizes the iodide ion to produce iodine which attacks the starch to give the blue-black color
  D) iodine attacks the starch to give the blue-black color
  Show Answer
  The correct answer is C .
• Question 245:

  Which of the following mixtures is an example of a colloid?

  Options:
  A) Milk
  B) Orange juice
  C) Saltwater
  D) Sugar dissolved in water
  Show Answer
  The correct answer is A .
• Question 246: The alkyl group is represented by the general formula Options:
  A) C_nH₂n
  B) C_nH₂n − 2
  C) C_nH₂n + 1
  D) C_nH₂n + 2
  Show Answer
  The correct answer is C .
• Question 247:

  Proteins in acid solution undergo?

  Options:
  A) Substitution
  B) Fermentation
  C) Hydrolysis
  D) Polymerisation
  Show Answer
  The correct answer is C .
• Question 248: The commonest feature of reactions at the anode is that Options:
  A) electrons are consumed
  B) oxidation is involved
  C) ions are reduced
  D) electrode dissolves
  Show Answer
  The correct answer is B .
• Question 249:

  What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours, through molten magnesium chloride?
  [1 faraday = 96500C, Mg = 24]

  Options:
  A) 1.12g
  B) 4.48g
  C) 1.80g
  D) 2.00g
  Show Answer
  The correct answer is C .
• Question 250: In a neutralization reaction involving HCI and NaOH using litmus as indicator, the colour at the end point is Options:
  A) Blue
  B) Red
  C) Orange
  D) Purple
  Show Answer
  The correct answer is C .