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 261: The characteristics reaction of carbonyl compounds is? Options:
  A) substitution
  B) elimination
  C) addition
  D) saponfication
  Show Answer
  The correct answer is C .
• Question 262: Water can be obtained as the only product during the Options:
  A) combustion of hydrocarbons
  B) neutraliization of an acid by base
  C) combustion of hydrogen
  D) electrolysis of brine
  Show Answer
  The correct answer is C .
• Question 263:

  

  Use the graph above to answer this question. The mass of a substance, M, liberated at an electrode during electrolysis is proportional to the quantity of electricity, Q passing through the electrolyte. This is represented graphically by.

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is A .
• Question 264: The oxidation state of oxygen in tetraoxosulphate(IV) acid is Options:
  A) -4
  B) +4
  C) -2
  D) +2
  Show Answer
  The correct answer is C .
• Question 265: One note of a hydrocarbon 36g of carbon and its density is 20. The structure of hydrocarbon is (organic chemical) Options:
  A) CH3C = CH
  B) CH3CH = CH2
  C) CH3CH2C = CH
  D) CH33CH2CH3
  Show Answer
  The correct answer is A .
• Question 266: Sodium metal is always kept under oil because it Options:
  A) Readily reacts with water
  B) Is reduced by atmospheric nitrogen
  C) Reacts vigorously on exposure to air
  D) Reacts with oxygen and carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 267: Which of the following types of bonding does not involve the formation of new substance? Options:
  A) Metallic
  B) covalent
  C) Co-ordinate
  D) Electrovalent
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  The correct answer is A .
• Question 268:

  0.16g of methane when burnt raises the temperature of 100g of water by 40°C. What is the of combustion of methane when if the heat capacity of water is 4.2 Jg^-1°C^-1?

  (CH₄ = 16)

  Options:
  A) 1,160 kJ mol^-1
  B) 1,180 kJ mol^-1
  C) 1,560 kJ mol^-1
  D) 1,600kJ mol^-1
  E) 1,680 kJ mol^-1
  Show Answer
  The correct answer is E .
• Question 269: $PC{l}_{5(g)}\to PC{l}_{3(g)}+C{l}_{2(g)}$
  In the reaction above, an increase in pressure will Options:
  A) decelerate the reaction
  B) Increase the yield of $PC{l}_3$
  C) increase the yield of $PC{l}_5$
  D) accelerate the reaction
  Show Answer
  The correct answer is C .
• Question 270: Which of the following separation processes is most likely to yield high quality ethanol (>95%) from palm wine? Options:
  A) Fractional distillation without a dehydrant
  B) simple distillation with a dehydrant
  C) fractional distillation with a dehydrant
  D) column chromatography
  E) evaporation
  Show Answer
  The correct answer is C .