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 561:

  A current of 10.0A was passed for 1 hour through a solution of copper (ll) sulphate between the copper electrodes. Which of the following observation would be correct?

  (1 Faraday = 96,500 coulobms) (i) 0.186 mole of copper is dissolved from the anode. (ii) 0.372 mole of copper is deposited on the cathode. (iii) the original Cu²⁺ ion concentration of the solution remains unchanged. (iv) the original Cu²⁺ ion concentration of the solution decreases.

  Options:
  A) i and ii
  B) i and iii
  C) i and iv
  D) ii and iii
  E) ii and iv
  Show Answer
  The correct answer is B .
• Question 562:

  In the upper atmosphere, the ultra-violet light breaks off a free chlorine atom from chlorofluorocarbon molecule. The effect of this is that the free chlorine atom will

  Options:
  A) be very reactive and will attack ozone
  B) be non-reactive and will not attack ozone
  C) not change the level of ozone in the atmosphere
  D) increase the level of ozone in the atmosphere
  Show Answer
  The correct answer is A .
• Question 563:

  Which of the following is a common property of non-metals?

  Options:
  A) Exist as solids at room temperature
  B) Tend to gain electrons in chemical reactions
  C) High thermal conductivity
  D) Readily form cations in chemical reactions
  Show Answer
  The correct answer is B .
• Question 564:

  A colourless organic compound X was burnt in excess air to give two colourless and odourless gases, Y and Z, as products. X does not decolorize blue bromine vapour, Y turns lime milky while Z gives a blue colour with copper (ll) tetraoxosulphate (IV).

  Y and Z are respectively?

  Options:
  A) CO₂ and NH₃
  B) CO and NH₃
  C) SO₂ and H₂O
  D) CO₂ and H₂O
  E) SO₂ and NH₃
  Show Answer
  The correct answer is D .
• Question 565: If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso₂ and Rch₄ will be in the ratio? (S = 32, O = 16, C = 12, H = 1) Options:
  A) 4:1
  B) 2:1
  C) 1:2
  D) 1:4
  Show Answer
  The correct answer is C .
• Question 566: Which of the following is acceptable as the organic product of the reaction of ethanoic acid and ethanol with an acid catalyst? Options:
  A) Ethyl ethanoate
  B) Methyl ethanoate
  C) Ethyl methyl ketone
  D) Butanol
  E) None
  Show Answer
  The correct answer is A .
• Question 567: Sodium chloride has no solubility product value because of its? Options:
  A) saline nature
  B) high solubility
  C) low solubility
  D) insolubility
  Show Answer
  The correct answer is B .
• Question 568: Sulphur Options:
  A) forms two alkaline oxides
  B) is spontaneously flammable
  C) burns with a blue flame
  D) conducts electricity in the molten state
  E) is usually stored in the form of sicks in water
  Show Answer
  The correct answer is C .
• Question 569: A common characteristic between zinc and the other transition elements is the ability to Options:
  A) have variable oxidation states
  B) from complex ions
  C) act as a catalyst
  D) from coloured ions
  Show Answer
  The correct answer is B .
• Question 570: Element X has a total of 19 electrons and can react with oxygen to form an oxide. Which of the following statements is NOT true of the oxide of the element? Options:
  A) When exposed to air, it slowy changes to liquid
  B) its solution in water conducts electricity
  C) Its solution in water, on evaporationm gives a white solid
  D) Its solution in water liberates hydroge when in contact with aluminium metal
  E) Its oxide, when stronlgy heated, regenerates the elements X
  Show Answer
  The correct answer is A .