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 941: The production of ammonia by the haber process may be represented by the equilibrium equation N₂(g) + 3H₂(g) ↔ 2NH₃ ∆H = -22KJ. Therefore the production of ammonia will be favoured by? Options:
  A) only high pressure
  B) only high temperature
  C) a combination of high temperature and low pressure
  D) a combination of low temperature and high pressure
  E) low pressure
  Show Answer
  The correct answer is D .
• Question 942: How many isomers does pentane have? Options:
  A) 6
  B) 5
  C) 4
  D) 3
  Show Answer
  The correct answer is D .
• Question 943: An element, Z froms an anion whose formula is [Z(CN)₆]^y. If Z has an oxidation number of +2, what is the value of y? Options:
  A) - 2
  B) - 3
  C) - 4
  D) - 5
  Show Answer
  The correct answer is C .
• Question 944: Sodium and potassium belong to the same group of the Periodic Table. This is because? Options:
  A) both are metals
  B) both are soft and lighter than water
  C) both form cations by losing electrons
  D) both have identical electronic configuration
  E) both react with water vigorously
  Show Answer
  The correct answer is D .
• Question 945: The ability of carbon to form long chains is referred to as Options:
  A) Alkylation
  B) Acylation
  C) Carbonation
  D) Catenation
  Show Answer
  The correct answer is D .
• Question 946: The soft solder used for welding and plumbing is alloy of Options:
  A) lead and tin
  B) iron and tin
  C) lead and zinc
  D) iron and zinc
  Show Answer
  The correct answer is A .
• Question 947: Ordinary glass is manufactured from silica, CaCO₃ and Options:
  A) Na₂CO₃
  B) K₂CO₃
  C) K₂SO₄
  D) NaHCO₃
  Show Answer
  The correct answer is A .
• Question 948: The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains Options:
  A) 78 protons and 55 elections
  B) 55 protons and 78 neutrons
  C) 55 neutrons 78 electrons
  D) 78 protons and 55 neutrons
  Show Answer
  The correct answer is B .
• Question 949:

  At 25^o and zymase as catalyst,

  C₆H₁₂₆ → 2C₂H₅OH + 2CO₂ + energy

  The reaction above represented by the equation above is useful in the production of

  Options:
  A) propanol
  B) butanol
  C) methanol
  D) ethanol
  Show Answer
  The correct answer is D .
• Question 950: Which of the following combinations of conditions may increase the rate of a chemical reaction? Options:
  A) Decrease in temperature, increase in concentration of the reactants
  B) Increase in temperature, addition of a catalyst, decrease in the surface area of the reactants
  C) Increase in temperature, increase in concentration, addition of a catalyst and increase in the surface area of the reactants
  D) Decrease in temperature concentration and surface area of the reactants
  E) Additionof a catalyst and in the absence of light
  Show Answer
  The correct answer is C .