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 1821:

  

  In the diagram above, R is a mixture of

  Options:
  A) potassium tetraxochlorate (VII) and concentrated H₂SO₄
  B) potassium trioxochlorate (V) and concentrated H₂SO₄
  C) potassium tetratoxomanganate (VII) and concentrated HCI
  D) manganes (IV) oxide and concentrated HCI
  Show Answer
  The correct answer is D .
• Question 1822: Cr₂O₇ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ +6Fe³⁺ + 7H₂O. In the above , the oxidation number of chromium changed from? Options:
  A) +7 to +3
  B) +6 to +3
  C) +5 to +3
  D) -2 to +3
  Show Answer
  The correct answer is A .
• Question 1823: The thermal decomposition of copper (ll)trioxonitrate (V) yields copper (ll) oxide, oxygen and? Options:
  A) nitrogen (ll) oxide
  B) nitrogen (l) oxide
  C) nitrogen (lV) oxide
  D) nitrogen
  Show Answer
  The correct answer is C .
• Question 1824: When the two end alkyl groups ethyl ethanoate are interchange, the compound formed is known as Options:
  A) methyl ethanoate
  B) ethyl propanaote
  C) methyl propanoate
  D) propyl ethanoate
  Show Answer
  The correct answer is C .
• Question 1825: The energy value of petrol can be determined by a Options:
  A) bomb calorimeter
  B) catalytic cracker
  C) fractionating column
  D) thermometer
  Show Answer
  The correct answer is C .
• Question 1826: In the production of soap, concentrated sodium chloride solution is added to Options:
  A) Increase the solubility of soap
  B) Decrease the solubility of the soap
  C) Saponify the soap
  D) Emulsify the soap
  Show Answer
  The correct answer is B .
• Question 1827:

  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 1828: Which of the following types of alkanols undergo oxidation to produce alkanoic acids? 1. Primary alkanols 11. Secondary alkanols 111. Tertiary alkanols Options:
  A) 1,11 and 111
  B) l and ll only
  C) ll only
  D) l only
  Show Answer
  The correct answer is D .
• Question 1829:

  

  In the diagram above. X is

  Options:
  A) SO₃
  B) SO₂
  C) S
  D) H₂S
  Show Answer
  The correct answer is B .
• Question 1830:

  In the reactions

  (I) H₂ (g) + 1/2O₂(g) → H₂O(l); ∆H = -286 KJ

  (II) C(s) + O₂g) → CO₂ (g); ∆H = -406 KJ the equations imply that

  Options:
  A) more heat is absorbed in (l)
  B) more heat is absorbed in (ll)
  C) less heat is evolved in (l)
  D) reaction (ll) proceeds faster than (l)
  E) reaction (l) proceeds faster than (ll)
  Show Answer
  The correct answer is C .