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 1981:

  

  Choose the correct option from the graph above.

  3Fe_(S) + 4H₂O_(g) ⇌ Fe₃O_4(s) + 4H_2(g). The equilibrium constant, K, of the reaction above is represented as

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is C .
• Question 1982: The alloy duralumin is used for the building of aeroplanes because it? Options:
  A) asborbs heat readily from sure thereby preventing the inside of the plane from getting cold at high attitudes
  B) reflects sunlight readily, thereby keeping the inside of the plane cool
  C) is extremely durable and possesses reflective ability
  D) is easily the lightest building material
  E) possesses both strenght and lightness
  Show Answer
  The correct answer is E .
• Question 1983:

  Which of the following is a redox reaction?

  Options:
  A) KCI_(aq) + H₂SO_4(aq) → KHSO_4(aq) + HCI_(aq)
  B) 2FeBr_2(aq) + Br_4(aq) → 2FeBr_3(aq)
  C) 3AgNO_(aq) + FeCl_3(aq) → 3AgCl_(aq) + Fe(NO₃)_3(aq)
  D) H₂CO_3(aq) → H₂O_(I)2- + CO_2(g)
  Show Answer
  The correct answer is B .
• Question 1984: In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl Options:
  A) Cl₂ is reduced because it has lost electrons
  B) Cl₂ is reduced because its oxidation number has decreased
  C) Cl₂ is reduced because its molecule is change to two ions
  D) Fe²⁺ is reduced because it has lost electrons
  E) Fe²⁺ is reduced because it has gained electrons
  Show Answer
  The correct answer is B .
• Question 1985: An endothermic reaction is one during which heat is.....and can be represented by the symbol.... which of the following combinations can be used accurately to complete the above definition? Options:
  A) liberated, -$\mathrm{\Delta }$H
  B) liberated, +$\mathrm{\Delta }$H
  C) absorbed, -$\mathrm{\Delta }$H
  D) absorbed, +$\mathrm{\Delta }$H
  E) absorbed, +$\mathrm{\Delta }$G
  Show Answer
  The correct answer is D .
• Question 1986: A suitable reagent for distinguish between ethanoic and ethanol is Options:
  A) bromine water
  B) Fehling’s solution
  C) sodium hydrogen trioxocarbonate (iv)
  D) Ammoniacal silver trioxonitrate(V)
  Show Answer
  The correct answer is C .
• Question 1987:

  Which of the following is an example of a chemical change?

  Options:
  A) dissolution of salt in water
  B) rusting of iron
  C) melting of ice
  D) separating a mixture by distillation
  Show Answer
  The correct answer is B .
• Question 1988: What is discharged at the cathode during the electrolysis of copper (ll) tetraoxosulphate (VI) solution? Options:
  A) Cu ²⁺ only
  B) H + only
  C) Cu ²⁺ and H
  D) Cu ²⁺ and SO ^2-
  Show Answer
  The correct answer is A .
• Question 1989: If 24.4 g of lead (ll) trioxonitrate (V) were dissolved in 42 g of distilled water at 20^oC; calculate the solubility of the solute in gdm^-3. Options:
  A) 581.000.
  B) 0.581
  C) 5.810
  D) 58.100
  Show Answer
  The correct answer is A .
• Question 1990: When chlorine is passed into water and subsequently exposed to sunlight, the gas evolved is? Options:
  A) HCl
  B) HOCl
  C) O₂
  D) Cl₂O
  Show Answer
  The correct answer is C .