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 471: What is the consequences of increasing pressure on the equilibrium reaction ZnO_(s) + H_2(g) Zn_(s) + H₂O_(I)? Options:
  A) The equilibrium is driven to the left
  B) The equilibrium is driven to the right
  C) There is no effect
  D) More ZnO is produced
  Show Answer
  The correct answer is C .
• Question 472: N₂O_4(g) ↔ 2NO_2(g). Increase in total pressure of the equilibrium reaction above will Options:
  A) produce more of NO_2(g) in the mixture
  B) convert all of N₂O_4(g) to NO_2(g)
  C) have no effect on the concentrations of NO_2(g)and N₂O_4(g)
  D) produce more of N₂O_4(g) in the mixture
  Show Answer
  The correct answer is D .
• Question 473: Which of the following questions is correct about the periodic table? Options:
  A) The non-metallic properties of the elements tend to decrease across each period
  B) The valence electrons of the elements increase progressively across the period
  C) Elements in the same group have the same numbeer of electron shells
  D) Elements in the same period have the number of valence electrons
  Show Answer
  The correct answer is B .
• Question 474: On heating anhydrous iron (ll) sulphate, in addition to producing iron (iii) oxide, which of the following is produced? Options:
  A) SO₂ (g) + FeS (s)
  B) SO₃ (g) +FeS(s)
  C) SO₂ (g) + SO₃(g)
  D) SO₂ (g) + H₂S (g)
  E) SO₃(g) + H₂S(g)
  Show Answer
  The correct answer is C .
• Question 475: In countries where the temperature fall below 273k, salt always spilled on the ray road in order to Options:
  A) increase the making point office
  B) increase the density of the ice
  C) make the ice impure
  D) rinse the making point of the ice
  Show Answer
  The correct answer is A .
• Question 476: Which of the following ions require the largest quantity of electricity for discharge at an electrode? Options:
  A) 2.0 mole of Q ³⁺
  B) 2.5 mole of R²⁺
  C) 4.0 mole of Y^-
  D) 3.0 mole of T^-
  Show Answer
  The correct answer is A .
• Question 477: Clothes should be properly rinsed with water after bleaching because Options:
  A) the bleach decolourizes the clothes
  B) chlorine reacts with fabrics during bleaching
  C) the clothes are sterilized during bleaching
  D) hydrogen chloride solution is produced during bleaching
  Show Answer
  The correct answer is D .
• Question 478:

  Sodium sulphate decahydrate (Na₂SO₄.10 H₂O) on exposure to air loses all its water of crystallization.

  The process of loss is known as

  Options:
  A) efflorescence
  B) hygroscopy
  C) deliquescence
  D) effervescence
  E) dehydration
  Show Answer
  The correct answer is A .
• Question 479: Commercial bleaching can be carried out using Options:
  A) sulphur (IV) oxide and ammonia
  B) hydrogen sulphide and chlorine
  C) chlorine and sulphur (IV) oxide
  D) ammonia and chlorine
  Show Answer
  The correct answer is C .
• Question 480:

  An element used in the production of matches is

  Options:
  A) nitrogen
  B) aluminium
  C) copper
  D) sulphur
  Show Answer
  The correct answer is D .