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 131: The reddish-brown rust on iron roofing sheets consists of Options:
  A) Fe³⁺(H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H₂O
  Show Answer
  The correct answer is C .
• Question 132:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 133:

  A secondary alkanol can be oxidized to give an

  Options:
  A) alkanone
  B) alkyne
  C) alkanoic acid
  D) alkanal
  Show Answer
  The correct answer is A .
• Question 134:

  What technique is suitable for separating a binary solution of potassium chloride and potassium trioxochlorate (V)?

  Options:
  A) Fractional crystallization
  B) Fractional distillation
  C) Filtration
  D) Evaporation
  Show Answer
  The correct answer is A .
• Question 135:

  A 'breath test' used by traffic police to check drunken driving uses?

  Options:
  A) Tumeric on filter paper
  B) Silica gel coated with saliva nitrate
  C) Potassium permanganate-sulphuric acid
  D) Potassium dichromatic-sulphuric acid
  Show Answer
  The correct answer is D .
• Question 136: The fraction of crude oil used as jet fuel is Options:
  A) refinery gas
  B) diesel oil
  C) kerosine
  D) gasoline
  Show Answer
  The correct answer is C .
• Question 137: Deliquescent substance are used for Options:
  A) Cooling
  B) Wetting
  C) Melting
  D) Drying
  Show Answer
  The correct answer is D .
• Question 138: The gas that is most useful in protecting humans against solar radiation is Options:
  A) chlorine
  B) ozone
  C) carbon (IV) oxide
  D) hydrogen sulphide
  Show Answer
  The correct answer is B .
• Question 139: The chemical used for coagulation in water purification is Options:
  A) Aluminium tetraoxosulphate (VI)
  B) Copper tetraoxosulphate (VI)
  C) Sodium tetraoxosulphate (VI)
  D) Calcium tetraoxosulphate (VI)
  Show Answer
  The correct answer is A .
• Question 140: Which of the following statements is true? Options:
  A) an increase in the temperature of a given mass of gas increases the number of gas molecules
  B) an increase in the temperature of the gas does not affect the kinetic energy
  C) an increase in the pressure of the gas is proportional to the increase in volume
  D) a decrease in the pressure of a gas is proportional to the decrease in volume at constant temperature
  E) a decrease in the pressure of the gas decreases the number of gas molecules present
  Show Answer
  The correct answer is D .