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 491:

  

  The compound above is the product of the oxidation of

  Options:
  A) 2-methlbutan-2-ol
  B) 2-methylbutan -1- ol
  C) 2, 3-dimethylprop 1-ol
  D) Pentan -2- ol
  Show Answer
  The correct answer is B .
• Question 492: In which of the following processes is iron being oxidized?1 Fe + H₂SO₄ → FeSO₄ +H₂2 FeSO₄ + H₂S → FeS + H₂SO₄3 2FeCI₂ + Cl₂ → 2FeCl₃4 2FeCl₃ + SnCl₂ + → 2FeCl₂ + SnCl₄ Options:
  A) 1 only
  B) 2 only
  C) 3 only
  D) 1 and 3
  E) 2 and 4
  Show Answer
  The correct answer is D .
• Question 493: The catalyst used in the contact process for the manufacture of tetraoxosulphate (VI) acid is Options:
  A) manganes (IV) oxide
  B) manganese (ll) tetraoxosulphate (VI)
  C) vanadium (V) oxide
  D) iron metal
  Show Answer
  The correct answer is C .
• Question 494: The molecular formula of a common organic laboratory anaesthetic is Options:
  A) CHCl₃
  B) CHI₃
  C) CCl₄
  D) CHF₃
  Show Answer
  The correct answer is A .
• Question 495: The atomic number of an element whose cation, X²⁺, has the ground state electronic configuration 1s²2s²2p⁶3s²2p⁶ is? Options:
  A) 16
  B) 18
  C) 20
  D) 22
  E) 24
  Show Answer
  The correct answer is C .
• Question 496:

  Balance the following redox reaction:
  Fe${}_2$O${}_3$+ CO Fe + CO${}_2$

  Options:
  A) Fe${}_2$O${}_3$ + CO → 2Fe + 2CO${}_2$
  B) 2Fe${}_2$O${}_3$ + 3CO → 4Fe + 3CO${}_2$
  C) Fe${}_2$O${}_3$ + 2CO → 2Fe + 2CO${}_2$
  D) Fe${}_2$O${}_3$ + 3CO → 2Fe + 3CO${}_2$
  Show Answer
  The correct answer is D .
• Question 497: In which of the following is the entropy change positive? Options:
  A) H₂O_(I) → H₂O_(g)
  B) Cu²⁺_{(aq) + Fe(s)} → Fe⁽²⁺⁾ + Cu_(s)
  C) N_2(g) + 3H_2(g) → 2NH_3(g)
  D) 2HCI_(s) → H_2(g) + CI_2(g)
  Show Answer
  The correct answer is A .
• Question 498: The relative atomic mass of a naturally occurring lithium consisting of 90% Li and 10% Li is Options:
  A) 6.9
  B) 7.1
  C) 6.2
  D) 6.8
  Show Answer
  The correct answer is C .
• Question 499:

  Mg_(s) + 2HCl_(aq) → MgCl_2(aq) + H_2(g)

  From the equation above, the mass of magnesium required to react with 250cm³ of 0.5M HCl is

  [Mg = 24]

  Options:
  A) 0.3g
  B) 1.5g
  C) 2.4g
  D) 3.0g
  Show Answer
  The correct answer is B .
• Question 500: In the laboratory preparation of trioxonitrate (V) acid the nitrogen(iv) oxide formed as a by-product is removed by Options:
  A) further heating
  B) adding concentrated H₂SO₄
  C) cooling the acid solution with cold water
  D) bubbling air through the acid solution
  Show Answer
  The correct answer is D .