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 181: If the difference in electronegativity of elements P and Q is 3.0. The bond that will be formed between them is Options:
  A) metallic
  B) covalent
  C) co-ordinate
  D) ionic
  Show Answer
  The correct answer is D .
• Question 182: Cu₂S_(s) + O2(g) = 2CU_(s) + SO2_2(g) Options:
  A) +1 to 0
  B) 0 to +2
  C) +2 to +1
  D) 0 to +1
  Show Answer
  The correct answer is A .
• Question 183: Which of the following statements is true of sulphur (IV) oxide? Options:
  A) It forms tetraoxosulphate (VI) acid with water
  B) It is an odourless gas
  C) It is an acid hybride
  D) It forms white precipitate with acidified barium chloride
  Show Answer
  The correct answer is C .
• Question 184:

  The process of rusting is an example of the formation of

  Options:
  A) Basic oxide
  B) Acidic oxide
  C) Reducing oxide
  D) Amphoteric oxide
  Show Answer
  The correct answer is A .
• Question 185:

  N₂O_4(aq) $\rightleftharpoons$ 2NO_2(g) $△$H = +ve

  In the reaction above, an increase in temperature will

  Options:
  A) Increase the reactant production
  B) Increase the value of the equilibrium constant
  C) Shift the equilibrium to the left
  D) Decrease the value of the equilibrium constant
  Show Answer
  The correct answer is B .
• Question 186: On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as Options:
  A) efflorescence
  B) diliquescence
  C) hygroscopy
  D) hydrolysis
  Show Answer
  The correct answer is A .
• Question 187: The property which makes alcohol soluble in water is the Options:
  A) boiling point
  B) hydrogen bonding
  C) ionic character
  D) covalent nature
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  The correct answer is B .
• Question 188:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  Reaction of X with yeast forms the basis of the

  Options:
  A) plastic industry
  B) textile industry
  C) brewing industry
  D) soap industry
  E) dyeing industry
  Show Answer
  The correct answer is C .
• Question 189: The bleaching action of chlorine gas is effective due to the presence of Options:
  A) hydrogen chloride
  B) water
  C) air
  D) oxygen
  Show Answer
  The correct answer is B .
• Question 190:

  C₃H₅ - COH₃ =CH₂

  The IUPAC nomenclature of the structure above is

  Options:
  A) 3-methybut-3-ene
  B) 2-methylbut-1-ene
  C) 2-ethylprop-1-ene
  D) 2-methylbut-2-ene
  Show Answer
  The correct answer is B .