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 91: What is the valence shell electron configuration of the element with atomic number 17? Options:
  A) 1s² 2s² 2p⁶ 3s² 3p⁴
  B) 1s² 2s² 2p⁶ 3s² 3p⁵
  C) 2s² 2p⁶
  D) 3s² 3p⁵
  Show Answer
  The correct answer is B .
• Question 92:

  The chlorinated alkane often used industrially to remove grease is?

  Options:
  A) Tetrachloromethane
  B) Chloromethane
  C) Trichloromethane
  D) Dichloromethane
  Show Answer
  The correct answer is A .
• Question 93:

  The gas which causes global warming is?

  Options:
  A) O${}_2$
  B) CO${}_2$
  C) N${}_2$
  D) He
  Show Answer
  The correct answer is B .
• Question 94: Which of the following is used as an 'anti-knock' in automobile engines? Options:
  A) Tetramethyl silane
  B) Lead tetra-ethyl
  C) Glycerol
  D) n-heptane
  Show Answer
  The correct answer is B .
• Question 95:

  The enzyme that converts glucose to ethylalcohol is?

  Options:
  A) maltase
  B) zymase
  C) Diatase
  D) Invertase
  Show Answer
  The correct answer is B .
• Question 96: The pressure of 100cm³ of oxygen at 35^oC is 750mmHg. What will be the volume of gas if the pressure is reduced to 100mmHg without changing the temperature? Options:
  A) 650 cm³
  B) 850 cm³
  C) 580 cm³
  D) 750 cm³
  Show Answer
  The correct answer is D .
• Question 97:

  Consider the reaction: A + 2B${}_{(g)}\rightleftharpoons$ 2C + D${}_{(g)}$ ($\mathrm{\Delta }$H = +ve)

  What will be the effect of decrease in temperature on the reaction?

  Options:
  A) Rate of backward reaction will increase
  B) The equilibrium constant will shift
  C) Rates of forward and backward reactions are not affected
  D) Rate of forward reaction will increase
  Show Answer
  The correct answer is A .
• Question 98:

  What is the chemical formula of rust, which is formed on the surface of iron in the presence of oxygen and moisture?

  Options:
  A) Fe${}_3$O${}_4$
  B) FeO
  C) Fe(OH)3
  D) Fe${}_2$O${}_3$
  Show Answer
  The correct answer is D .
• Question 99: The compounds CH₃CH₂CHO and CH₃COCH₃ can be distinguished from each other using Options:
  A) Dilute ammonia
  B) Benedict's solution
  C) Tollen's reagent
  D) Sodium hydroxide solution
  Show Answer
  The correct answer is C .
• Question 100:

  Which of the following pairs cannot be represented with a chemical formula?

  Options:
  A) air and bronze
  B) bronze and sodium chloride
  C) copper and sodium chloride
  D) caustic soda and washing soda
  Show Answer
  The correct answer is A .