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 1:

  If 100 cm³ of oxygen pass through a porous plug in 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is?

  (O = 16, H = 1)

  Options:
  A) 10.0 s
  B) 12.5 s
  C) 17.7 s
  D) 32.0 s
  Show Answer
  The correct answer is B .
• Question 2: One mole of hydrocarbon contains 6g of hydrogen. If the molecular weight is 54, the hydrocarbon is an? Options:
  A) alkanone
  B) alkane
  C) alkene
  D) alkyne
  Show Answer
  The correct answer is D .
• Question 3: Neutral atoms of neon with atomic number 10 have the same number of electron as Options:
  A) O²⁺
  B) Ca²⁺
  C) K⁺
  D) Mg²⁺
  Show Answer
  The correct answer is D .
• Question 4: 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 5: The type of reaction that is peculiar to benzene is Options:
  A) addition
  B) hydrolysis
  C) polymerization
  D) substitution
  Show Answer
  The correct answer is D .
• Question 6: The sulphide which is insoluble in dilute hydrochloric acid is Options:
  A) FeS
  B) CuS
  C) ZnS
  D) Na₂S
  Show Answer
  The correct answer is B .
• Question 7: The efficiency of a solid catalyst to increase reaction rates depends on its Options:
  A) surface area
  B) solubility
  C) concentration
  D) quantity
  Show Answer
  The correct answer is A .
• Question 8: In what respect will two dry samples of nitrogen gas differ from each other if sample 1 is prepared by completely removing CO₂ and O₂ from air, and sample 2 is prepared by passing purified nitrogen(i)oxide over heated copper? sample 1 is Options:
  A) purer than sample 2
  B) slightly denser than sample 2
  C) in all respects the same as sample 2
  D) colourless but sample 2 has a light brown colour
  E) slightly less reactive than sample 2
  Show Answer
  The correct answer is B .
• Question 9: What are the values of x, y and z respectively in the equation: xCu + yHNO₃ → xCu(NO₃)₂ + 4H₂O + zNO? Options:
  A) 4: 1: 2
  B) 3:8:2
  C) 2:8:3
  D) 8:3:2
  Show Answer
  The correct answer is B .
• Question 10: The alkyl group is represented by the general formula Options:
  A) C_nH₂n
  B) C_nH₂n − 2
  C) C_nH₂n + 1
  D) C_nH₂n + 2
  Show Answer
  The correct answer is C .