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 1441: If 24.4 g of lead (ll) trioxonitrate (V) were dissolved in 42 g of distilled water at 20^oC; calculate the solubility of the solute in gdm^-3. Options:
  A) 581.000.
  B) 0.581
  C) 5.810
  D) 58.100
  Show Answer
  The correct answer is A .
• Question 1442: The repeating unit in natural rubber is Options:
  A) alkyne
  B) isoprene
  C) n-propene
  D) peoprene
  Show Answer
  The correct answer is B .
• Question 1443: A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as? Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 1444: 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 1445: What is the volume of energy required to burn 45cm3 of mixture at S.T.P Options:
  A) 135.0cm³
  B) 150.0cm³
  C) 45.0cm³
  D) 90.0cm³
  Show Answer
  The correct answer is D .
• Question 1446: Starch can be converted to ethyl alcohol by? Options:
  A) distillation
  B) fermentation
  C) isomerization
  D) cracking
  Show Answer
  The correct answer is B .
• Question 1447: Which of the following molecules is held together by hydrogen bond? Options:
  A) CH₄
  B) HBr
  C) H₂SO₄
  D) HF
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  The correct answer is D .
• Question 1448: The confirmatory test for alkanoic acids in organic qualitative analysis is the? Options:
  A) turning of wet blue litmus paper red
  B) reaction with alkanols to form esters
  C) reaction with sodium hydroxide to form salt and water
  D) reaction with aqueous Na₂COsp₃ to liberate a gas which turns lime water milky
  Show Answer
  The correct answer is B .
• Question 1449: If the change in free energy of a system is -899 Jmol^-1 and the entropy change is 10Jmol^-1k^-1 at 250C, calculate the enthalpy change. Options:
  A) +2081 Jmol^-1
  B) -2081 Jmol^-1
  C) -649 Jmol^-1
  D) +649 Jmol^-1
  Show Answer
  The correct answer is A .
• Question 1450: When H₂S is passed into a solution of iron (III) chloride, the solution turns Options:
  A) Pale green
  B) Pale red
  C) Brown
  D) Colourless
  Show Answer
  The correct answer is A .