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 71: At 25^oC and 1atm, a gas occupies a volume of 1.50dm³. What volume will it occupy at 100^oC and 1atm? Options:
  A) 1.88 dm³
  B) 6.00 dm³
  C) 18.80 dm³
  D) 18.80 dm³
  E) 60.00dm³
  Show Answer
  The correct answer is A .
• Question 72:

  A chemical process in which there is a gain of electrons is known as?

  Options:
  A) Sublimation
  B) Reduction
  C) Oxidation
  D) Distillation
  Show Answer
  The correct answer is B .
• Question 73: Cathode rays cause an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays Options:
  A) are positively charged
  B) are negatively charged
  C) Have mass
  D) travel in straight lines
  Show Answer
  The correct answer is D .
• Question 74: What is observed when aqueous solutions of each of tetraoxosulphate (VI) acid, potassium trioxoiodate (V) and potassium iodide are mixed together? Options:
  A) A white precipitate is formed
  B) A green precipitate is formed
  C) The mixture remains colourless
  D) The mixture turns reddish brown
  Show Answer
  The correct answer is D .
• Question 75: How many isomers does pentane have? Options:
  A) 6
  B) 5
  C) 4
  D) 3
  Show Answer
  The correct answer is D .
• Question 76: What is the volume of oxygen required to burn complete 45 cm³ of methane at s.t.p? Options:
  A) 135.0 cm³
  B) 180.0 cm³
  C) 45.0 cm³
  D) 90.0 cm³
  Show Answer
  The correct answer is D .
• Question 77: Which of the following derivatives of nitrogen affords an aqueous solution having a pH of less that 7? Options:
  A) N₂O
  B) NO
  C) NO₂
  D) NaNO₃
  E) NH₃
  Show Answer
  The correct answer is C .
• Question 78: Which of the following compounds is used as a gaseous fuel? Options:
  A) CH₃ -CH₂ -CHO₂ -COOH
  B) CH₃ -C = CH
  C) CH₃ -CH₂ -CH₂ -CH₃
  D) CH₂ -CH₂ -CH₃
  Show Answer
  The correct answer is C .
• Question 79:

  A radioactive nucleus has a half-life of 20 years, starting with 100,000 particles, how many particles will be left exactly at the end of 40 years

  Options:
  A) 75,000 particles
  B) 35,000 particles
  C) 25,000 particles
  D) 50,000 particles
  Show Answer
  The correct answer is C .
• Question 80: The number of hydroxonium ions produced by one molecule of an acid in aqueous solution is its Options:
  A) basicity
  B) acid strength
  C) pH
  D) concentration
  Show Answer
  The correct answer is B .