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 1911: One of the following techniques can be used to show that chlorophyll pigment is a mixture of chemical compounds and not a single coloured compound Options:
  A) cystallization
  B) hydrolysis
  C) sublimation
  D) filtration
  E) chromatography
  Show Answer
  The correct answer is E .
• Question 1912: When platinum electrodes are used during the electrolysis of copper (ll) tetraoxosulphate (lV) solution, the solution gets progressively? Options:
  A) acidic
  B) basic
  C) neutral
  D) amphoteric
  Show Answer
  The correct answer is A .
• Question 1913:

  A solution X on mixing with AgNO₃ solution, gives a white precipitate solution in NH₃. A Solution Y, when added to X, also gives a white precipiate which is soluble on boiling. Solution Y contains?

  Options:
  A) Ag⁺ ion
  B) Pb²⁺ ion
  C) Pb⁴⁺ ion
  D) Zn²⁺ ion
  E) Al³⁺ ion
  Show Answer
  The correct answer is B .
• Question 1914: The pollutant that contributes to the depletion of the ozone layer is Options:
  A) CFCs
  B) NO₂
  C) SO₂
  D) CO
  Show Answer
  The correct answer is A .
• Question 1915:

  The ions X_- and Y₊ are isoelectronic, each containing a total of 10 electrons.

  How many protons are in the nuclei of the neutral atoms of X and Y respectively?

  Options:
  A) 10 and 10
  B) 9 and 9
  C) 11 and 9
  D) 9 and 11
  Show Answer
  The correct answer is D .
• Question 1916: When ammonium, potassium and calcium carbonates are each separately heated Options:
  A) none of them will decompose
  B) each of them will decompose to give carbondioxide and the respective oxide
  C) ammonium carbonate and potassium carbonate will not decompose
  D) only ammonium carbonate and the respective oxide
  E) ammonium carbonate will decompose to give carbondioxide, water and ammonia
  Show Answer
  The correct answer is D .
• Question 1917: What is the percentage of sulphur in sulphur (IV) oxide? Options:
  A) 66%
  B) 25%
  C) 40%
  D) 50%
  Show Answer
  The correct answer is D .
• Question 1918: What mass of sodium carbonate solution is in 500 cm³ of 0.1 molar sodium carbonate solution?(Na = 23, C = 12, O = 16) Options:
  A) 10.6 g
  B) 5.3 g
  C) 500 g
  D) 10 g
  E) 20 g
  Show Answer
  The correct answer is B .
• Question 1919: Ethanol reacts with excess acidified K₂Cr₂O to produce Options:
  A) ethanedioic acid
  B) ethanal
  C) ethylethanoate
  D) ethanoic acid
  Show Answer
  The correct answer is D .
• Question 1920:

  Which of the following are mixtures? 

  I. Petroleum 

  II. Rubber latex 

  III. Vulcanizer's solution 

  IV. Carbon sulphide

  Options:
  A) I, II and III
  B) I, II and IV
  C) I and II only
  D) I and IV
  Show Answer
  The correct answer is A .