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 1641: The balanced equation for the reaction of tetraoxosulphate(VI)acid with aluminium hydroxide to give water and aluminium tetraoxosulphate(VI) is Options:
  A) H₂SO₄ + Al(OH)₂ $\to$ 2H₂O + AlSO₄
  B) 3H₂SO₄ + 2Al(OH)₃ $\to$ 6H₂O + Al₂(SO₄)₃
  C) 3H₂SO₄ + 2AlH $\to$ 6H₂O + Al(SO₄)₃
  D) 3H₂ SO₄ + 2Al(OH)₃ $\to$ Al(SO₄)₃
  E) H₂SO₄ + Al(OH)₃ $\to$ H₂O + Al₂(SO₄)₃
  Show Answer
  The correct answer is B .
• Question 1642: A gas sample with an initial volume of 3.25 dm³ is heated and allowed to expand to 9.75 dm³ at constant pressure. What is the ratio of the final absolute temperature to the initial absolute temperature? Options:
  A) 3:1
  B) 5:2
  C) 5:4
  D) 8:3
  Show Answer
  The correct answer is A .
• Question 1643: A liquid begins to boil when? Options:
  A) its vapour pressure is equal to the vapour pressure of its solid at the given temperature
  B) molecules start escaping from its surface
  C) its vapour pressure equals the atmosphere pressure
  D) its volume is sightly increased
  Show Answer
  The correct answer is C .
• Question 1644: A pair of compounds that can be used to generate a gas which has physiological effect on human beings is Options:
  A) sodium trioxonitrate (V) and calcium chloride
  B) sodium dioxonitrate (III) and ammonium chloride
  C) sodium trioxonitrate (V) and ammonium chloride
  D) sodium dioxonitrate (III) and potassium chloride
  Show Answer
  The correct answer is A .
• Question 1645: Two atoms represented as U and U are? Options:
  A) isomers
  B) allotropes
  C) isotopes
  D) anomers
  Show Answer
  The correct answer is C .
• Question 1646: The pollution from petroleum spillage in rivers and lakes can best be dispersed by Options:
  A) Pouring detergents
  B) Passing of ships through the area
  C) Pouring organic solvents
  D) Evaporation
  Show Answer
  The correct answer is A .
• Question 1647: Which of the following is TRUE of Le Chatelier's Principle for an exothermic reaction? Options:
  A) Increase in temperature will cause an increase in the equilibrium constant
  B) Increase in temperature will cause a decrease in the equilibrium constant
  C) Addition of a catalyst will cause an increase in the equilibrium constant
  D) Addition of a catalyst will cause a decrease in the equilibrium constant
  Show Answer
  The correct answer is B .
• Question 1648: What is the percentage of sulphur in sulphur (IV) oxide? Options:
  A) 66%
  B) 25%
  C) 40%
  D) 50%
  Show Answer
  The correct answer is D .
• Question 1649:

  

  In the diagram above, gas X is

  Options:
  A) hydrogen
  B) chlorine
  C) oxygen
  D) hydrogen chloride
  Show Answer
  The correct answer is C .
• Question 1650: The molar ratio of oxygen to nitrogen in dissolved air is 2:1 whereas the ratio is 4:1 in atmospheric air because? Options:
  A) nitrogen is less soluble than oxygen
  B) oxygen is heavier than nitrogen
  C) nitrogen has a higher partial pressure in air
  D) gases are hydrated in water
  Show Answer
  The correct answer is A .