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 511:

  If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density.

  Options:
  A) 196
  B) 49
  C) 106
  D) 82
  Show Answer
  The correct answer is B .
• Question 512: A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is Options:
  A) O₂
  B) NO
  C) SO₂
  D) NH₃
  E) CO₂
  Show Answer
  The correct answer is C .
• Question 513:

  A colored gas that is known to be poisonous and can readily damage the mucous liningof the lungs is?

  Options:
  A) hydrogen sulphide
  B) carbon(ii)oxide
  C) chlorine
  D) sulphur(iv)oxide
  Show Answer
  The correct answer is C .
• Question 514: A substance that is used as a ripening agent for fruits is Options:
  A) ethene
  B) propene
  C) methane
  D) butane
  Show Answer
  The correct answer is A .
• Question 515:

  What is the mass (in grams) of 500 mL of ethanol? (density of ethanol = 0.789 g/mL)

  Options:
  A) 394.5 mL
  B) 500 mL
  C) 394.5 g
  D) 500 g
  Show Answer
  The correct answer is C .
• Question 516:

  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) C${}_3$H${}_6$O${}_3$
  B) C${}_6$H${}_6$O${}_3$
  C) C${}_6$H${}_{12}$O${}_6$
  D) CH${}_2$O
  Show Answer
  The correct answer is C .
• Question 517: An aqueous solution of a metal salt, M, gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia. Therefore cartion in M is Options:
  A) Zn ⁺⁺
  B) Ca⁺⁺
  C) Ai⁺⁺⁺
  D) Pb⁺⁺
  E) Cu⁺⁺
  Show Answer
  The correct answer is A .
• Question 518:

  An organic compound with a vapour density 56.5 has the following percentage composition:C =53.1% N = 12.4%, O = 28.3%, H = 6.2%. The molecular formula of the compound is

  Relative atomic masses: N = 14, O = 16, C = 12, H = 1 )

  Options:
  A) C₃H₆O₂N
  B) C₅H₆O₂N
  C) (C₅H₇O₂N)_1/2
  D) C₅H₇O₂N
  E) (C₅H₇O₂N)₂
  Show Answer
  The correct answer is D .
• Question 519: A common characteristic between zinc and the other transition elements is the ability to Options:
  A) have variable oxidation states
  B) from complex ions
  C) act as a catalyst
  D) from coloured ions
  Show Answer
  The correct answer is B .
• Question 520: In the reaction E+F ↔ G+H, the backward reaction is favoured if the concentration of Options:
  A) F is increased
  B) E is increased
  C) E is reduced
  D) G is reduced
  Show Answer
  The correct answer is C .