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 891:

  Cr₂O₇^2-_(aq) + 14H⁺_(aq) + 6l^-_(aq) → 2Cr³⁺_(aq) + 3l_(g) + 7H₂O_(I).

  The change in the oxidation number of oxygen in the equation above is?

  Options:
  A) 1
  B) 2
  C) 7
  D) 0
  Show Answer
  The correct answer is D .
• Question 892: Which of the following is an electrolyte? Options:
  A) Alcohol
  B) Sodium acetate solution
  C) Solid potassium hydroxide
  D) Mercury
  Show Answer
  The correct answer is B .
• Question 893: Which of the following raw materials would be required from the smelting of iron ore in a blast furnace? Options:
  A) CaCO ₃
  B) Zn(NO₃)₂
  C) CuSO₄
  D) AICI₃
  E) CaSO₄
  Show Answer
  The correct answer is A .
• Question 894: The temperature of a body decreases when drops of liquid placed on it evaporate because? Options:
  A) the atmospheric vapour pressure has a cooling effect on the body
  B) a temperature gradient exists between the drops of liquid and the body causing the latter to vaporate
  C) the heat of vapourization is drawn from the body causing it to cool
  D) the random motion of the liquid molecules causes a cooling effect on the body
  Show Answer
  The correct answer is C .
• Question 895:

  Which of the following is an example of a primary cell?

  Options:
  A) Alkaline battery
  B) Nickel-cadmium battery
  C) Lead-acid battery
  D) Lithium-ion battery
  Show Answer
  The correct answer is A .
• Question 896:

  What is the main source of carbon monoxide (CO) in urban areas?

  Options:
  A) Volcanic eruptions
  B) Vehicle emissions
  C) Forest fires
  D) Industrial processes
  Show Answer
  The correct answer is B .
• Question 897:

  An organic compound with fishy smell is likely to have a general formula?

  Options:
  A) RCONHR${}^1$
  B) RCONH${}_2$
  C) RNH${}_2$
  D) RCOR${}^1$
  Show Answer
  The correct answer is C .
• Question 898:

  With conc H₂SO₄ as catalyst

  CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

  Options:
  A) esterification
  B) Condensation
  C) saponification
  D) neutralization
  Show Answer
  The correct answer is A .
• Question 899: Which of the following sets of metals dissolves in dilute HCl? Options:
  A) Fe, Sn and Cu
  B) Mg, Fe and Cu
  C) Mg, Sn and Fe
  D) Cu, Mg and Sn
  Show Answer
  The correct answer is C .
• Question 900: Bronze is preferred to copper in the making of medals because it Options:
  A) is stronger
  B) can withstand low temperature
  C) is lighter
  D) has low tensile strength
  Show Answer
  The correct answer is A .