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 2201: 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 2202: Which of the following decreases when a given mass of gas is compressed to half its initial volume? Options:
  A) Average intermolecular distance
  B) Frequency of collisions
  C) Number of molecules present
  D) Atomic radius of each particle
  Show Answer
  The correct answer is A .
• Question 2203: In which of the following is the entropy change positive? Options:
  A) Thermal dissociation of ammonium chloride
  B) Reaction between an acid and a base
  C) Addition of concentrated acid to water
  D) Dissolution of sodium metal in water
  Show Answer
  The correct answer is A .
• Question 2204: 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 2205:

  

  The IUPAC nomenclature of the organic compound with the above structural formula is

  Options:
  A) 3-ethyl-2,5-dimethylhexane
  B) 4-ethyl-2,5-dimethylhexane
  C) 3-ethyl-2,5,5 - trimethylpentane
  D) 3-ethyl, 1,1,4-trimethylpentane
  Show Answer
  The correct answer is A .
• Question 2206: Complete hydrogenation of ethyne yields? Options:
  A) benzene
  B) methane
  C) ethane
  D) ethene
  E) propane
  Show Answer
  The correct answer is C .
• Question 2207:

  

  Use the graph above to answer this question.How long does it take all the solid to melt?`

  Options:
  A) 2.5 mins
  B) 6.0 mins
  C) 1.0 min
  D) 3.0 mins
  Show Answer
  The correct answer is A .
• Question 2208:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 2209: A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of? Options:
  A) nitrogen
  B) neon
  C) argon
  D) oxygen
  Show Answer
  The correct answer is D .
• Question 2210: The ion that can be used as an oxidizing agent is Options:
  A) Au³⁺
  B) Fe³⁺
  C) F^-
  D) Ca²⁺
  Show Answer
  The correct answer is C .