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 1741: Sodium hydroxide is prepared commercially from sodium chloride solution by? Options:
  A) electrolysis using mercury as cathode
  B) hydrolysis in steam using a catalyst
  C) electrolysis using iron as anode
  D) treating sodium chloride with ammonia and carbon (IV) oxide
  Show Answer
  The correct answer is A .
• Question 1742:

  

  Use the diagram above to answer this question. The activation energy of the uncatalysed reaction is

  Options:
  A) X
  B) X + Y
  C) X - Y
  D) Y
  Show Answer
  The correct answer is A .
• Question 1743: Which of the following bonds exist in crystalline ammonium chloride (NH₄Cl)? Options:
  A) Ionic and covalent
  B) Ionic and co-ordinate
  C) Ionic covalent and co-ordinate
  D) Covalent , co-ordinate and metalllic
  E) Ionic, covalent and metallic
  Show Answer
  The correct answer is C .
• Question 1744:

  Aluminium does not react with either dilute or concentrated trioxonitrate (V) acid because

  Options:
  A) it is insoluble in either dilute or concentrated trioxonitrate (V) acid
  B) it is lower than hydrogen in the electrochemical series
  C) the reaction with trioxonitrate (V) acid has a light activation energy
  D) an insoluble oxide is formed on its surface which renders it passive
  Show Answer
  The correct answer is D .
• Question 1745:

  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.

  The molecular formula of X is

  Options:
  A) C₁₂H₂₂O₁₁
  B) C₆H₁₂O₆
  C) C₃H₆O ₃
  D) C₇H₁₄O₇
  E) C₁₂H₆O₄
  Show Answer
  The correct answer is B .
• Question 1746: Detergents have the general formula? Options:
  A) R(CH₂)_nOH
  B) RSO₃^-Na⁺
  C) RSO^-₂Na⁺
  D) RSO₂H
  Show Answer
  The correct answer is B .
• Question 1747: Which of the following statements is true? When the potassium atom forms its ion Options:
  A) it gains one electron and becomes neutral
  B) its atomic number decreases
  C) it achieves electronic configuration of orgon
  D) it loses one proton
  E) it loses one neutron
  Show Answer
  The correct answer is C .
• Question 1748: What is the pH of 0.001 mol dm^-3 solution of sodium hydroxide Options:
  A) 14
  B) 13
  C) 12
  D) 11
  Show Answer
  The correct answer is D .
• Question 1749: The processes which return carbon (IV) oxide to the atmosphere include Options:
  A) respiration, decay and combustion
  B) photosynthesis, respiration and transpiration
  C) ozone depletion, combustion and decay
  D) photosynthesis, decay and respiration
  Show Answer
  The correct answer is A .
• Question 1750:

  Which of the compounds is composed of Al, Si, O and H?

  Options:
  A) Epson salt
  B) Limestone
  C) Clay
  D) Urea
  Show Answer
  The correct answer is C .