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 1041: Water for town supply is chlorinate to make it free from Options:
  A) bad colour
  B) bacteria
  C) temporary hardness
  D) permanent hardness
  Show Answer
  The correct answer is B .
• Question 1042:

  

  Use the graph above to answer this question.If the gas is cooled, at what temperature will it start to condense?

  Options:
  A) 125 ^oC
  B) 150^oC
  C) 175^oC
  D) 250^oC
  Show Answer
  The correct answer is B .
• Question 1043: Water is said to be temporarily hard when it contains Options:
  A) Ca (HCO₃)₂ and Mg (HCO₃)₂ salts
  B) Ca (HCO₃)₂ and CaCO₃ SALTS
  C) Mg(HCO₃)₂ and CaSO₄ salts
  D) CaSO₄ and Ca(HCO₃)₂ salts
  Show Answer
  The correct answer is A .
• Question 1044: Which of the following substances is a mixture? Options:
  A) Sulphur powder
  B) Bronze
  C) Distilled water
  D) Ethanol
  Show Answer
  The correct answer is B .
• Question 1045: Sodium chloride may be obtained from brine by Options:
  A) titration
  B) decantation
  C) distillation
  D) evaporation
  E) sublimation
  Show Answer
  The correct answer is D .
• Question 1046:

  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 1047:

  What is the valency of an element with the electronic configuration 2, 8, 7?

  Options:
  A) 7
  B) 1
  C) 2
  D) 3
  Show Answer
  The correct answer is B .
• Question 1048: Arrange HCI, CH₃COOH, C₆H₅CH₃ in order of increasing conductivity. Options:
  A) HCI, CH₃COOH, C₆H₅CH₃
  B) C₆H₅CH₃, HCI, CH₃COOH
  C) C₆H₅CH₃, CH₃COOH, HCI
  D) CH₃COOH, C₆H₅CH₃, HCI
  Show Answer
  The correct answer is C .
• Question 1049:

  Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

  Options:
  A) Fractional distillation
  B) Filtration followed by distillation
  C) Neutralization with sodium hydroxide followed by distillation
  D) Neutralization with sodium hydroxide followed by filtration
  Show Answer
  The correct answer is B .
• Question 1050:

  A given amount of gas occupies 10.0dm5 at 4atm and 273°C. The number of moles of the gas present is [Molar volume of gas at s.t.p = 22.4dm${}^3$]

  Options:
  A) 0.89 mol
  B) 1.90 mol
  C) 3.80 mol
  D) 5.70 mol
  Show Answer
  The correct answer is A .