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 1211: Which of the following is used in the manufacture of bleaching powder? Options:
  A) Sulphur dioxide
  B) Chlorine
  C) Hydrogen tetraoxosulphate (VI)
  D) Hydrogen sulphide
  E) Nitrogen dioxide
  Show Answer
  The correct answer is B .
• Question 1212:

  

  The solubility curve of a solid X (molecular mass = 160) is as show above 1,000 cm³ of a saturated solution of X at 80^oC. The weight of X crystalized out would be

  Options:
  A) 10 g
  B) 12 g
  C) 14 g
  D) 16 g
  E) 18 g
  Show Answer
  The correct answer is D .
• Question 1213: For a given solute, the concentration of its saturated solution in different solvents are Options:
  A) the same at the same temperature
  B) different at the same temperature
  C) the same at different temperature
  D) constant
  Show Answer
  The correct answer is B .
• Question 1214: An isomer of C₅H₁₂ is Options:
  A) 2–ethyl butane
  B) butane
  C) 2–methyl butane
  D) 2–methyl propane
  Show Answer
  The correct answer is C .
• Question 1215: A piece of sea shell, when dropped into a dilute solution of hydrochloric acid, produces a colourless, odourless gas which turns clear limewater milky. The sea shell contains Options:
  A) sodium chloride
  B) ammonium nitrate
  C) calcium carbonate
  D) calcium chloride
  E) magnesium chloride
  Show Answer
  The correct answer is C .
• Question 1216:

  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 1217: A blue solid, T, which weighed 5.0g was placed on a table. After 8 hours, the resulting pink solid was found to weigh 5.5g. It can be inferred that substance T? Options:
  A) is deliquescent
  B) is hydroscopic
  C) has some molecules of water of crystallization
  D) is efflorescent
  Show Answer
  The correct answer is A .
• Question 1218:

  

  Use the solubility curves below to answer questions. If 1 dm³ of a saturated solution of L at 60⁰C is cooled to 25⁰C, what amount in mole will separate out?

  Options:
  A) 0.75
  B) 0.25
  C) 1.00
  D) 0.50
  Show Answer
  The correct answer is A .
• Question 1219:

  

  The diagram above is the solubility curve of a solute, X. Find the amount of X deposited when 500cm³ of a solution of X is cooled from 60^oC to 20^oC.

  Options:
  A) 0.750 mole
  B) 0.950 mole
  C) 2.375 moles
  D) 4.750 moles
  Show Answer
  The correct answer is A .
• Question 1220: 10cm³ of CO is mixed and sparked with 100cm³ of air containing 21% O₂. If all the volumes measured at S.T.P. the volume of resulting gases would be? Options:
  A) 90cm³
  B) 100cm³
  C) 105cm³
  D) 110cm³
  E) 115cm³
  Show Answer
  The correct answer is C .