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 11:

  

  Copper sulphate solution was electrolysed using the apparatus show above. Which of the following changes are observed?

  Options:
  A) The bulb lights and copper is deposited at both electrodes
  B) the bulb lights and copper is deposited at the anode and disappears from the cathode
  C) the bulb lights and copper is deposited at the cathode and oxygen liberated at the anode
  D) the bulb lights and copper is deposited at the cathode and disappears from the anode
  E) the bulb lights but no additional changes are observed
  Show Answer
  The correct answer is D .
• Question 12: The conversion of open chain alkanes into cycloalkanes and aromatic compounds is called Options:
  A) cracking
  B) reforming
  C) isomerization
  D) polymerization
  Show Answer
  The correct answer is B .
• Question 13:

  2SO_2(g) + O_2(g) ↔ 2SO_3(g)

  ΔH = -189 kJ mol^-1

  The equilibrium constant for the reaction above is increased by

  Options:
  A) Increasing the temperature of the system
  B) Increase the pressure of the system
  C) The addition of a catalyst to the system
  D) Increasing the surface area of the vessel
  Show Answer
  The correct answer is B .
• Question 14: Deliquescent substances are also? Options:
  A) efflorescent
  B) anhydrous
  C) hygroscopic
  D) insoluble
  Show Answer
  The correct answer is C .
• Question 15:

  CH₂S_(g) + O_2(g) → 2Cn + SO_2(g)

  What is the change in the oxidation number of copper in the reaction?

  Options:
  A) 0 to + 2
  B) 0 to + 1
  C) C + 1 to 0
  D) + 2 to + 1
  Show Answer
  The correct answer is C .
• Question 16:

  5cm³ of a saturated solution of sodium chloride at 30°C gave, on careful evaporation, 1.95g of solid salt. The solubility of sodium chloride at 30°C?

  (Na = 23, Cl = 35.5)

  Options:
  A) 5.00 mole dm³
  B) 5.67 mole dm³
  C) 6.00 mole dm³
  D) 6.67 mole dm³
  E) 7.00 mole dm³
  Show Answer
  The correct answer is D .
• Question 17: The fuming of kettles is caused by the presence in the water of Options:
  A) Calcium tetraoxosulphate (VI)
  B) Calcium hydrogentrioxocarbonate (IV)
  C) Calcium hydroxide
  D) Calcium trioxocarbonate (IV)
  Show Answer
  The correct answer is B .
• Question 18:

  What is the concentration of a solution containing 2g of NaOH in 100cm³ of solution?

  [Na=23, O=16, H=1]

  Options:
  A) 0.05 moldm^-3
  B) 0.30 moldm^-3
  C) 0.50 moldm^-3
  D) 0.40 moldm^-3
  Show Answer
  The correct answer is C .
• Question 19:

  

  The compound above is the product of the oxidation of

  Options:
  A) 2-methlbutan-2-ol
  B) 2-methylbutan -1- ol
  C) 2, 3-dimethylprop 1-ol
  D) Pentan -2- ol
  Show Answer
  The correct answer is B .
• Question 20: An example of oxidation - reduction enzyme is Options:
  A) amylase
  B) protease
  C) lipase
  D) dehydrogenase
  Show Answer
  The correct answer is D .