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 311:

  Pure sulphuric acid is a liquid of 1:84 density. What volume of it would be required to prepare 250 cm³ of 2.0 M solution?

  (H = 1, S = 32, O = 16)

  Options:
  A) 2.00
  B) 2.66
  C) 3.00
  D) 3.66
  E) 4.00
  Show Answer
  The correct answer is B .
• Question 312: Mineral acids are usually added to commercial hydrogen peroxide to Options:
  A) oxidize it
  B) decompose it
  C) minimize its decomposition
  D) reduce it to water and oxygen
  Show Answer
  The correct answer is C .
• Question 313: Which of the following is used to hasten the ripening of fruit? Options:
  A) Ethene
  B) Ethanol
  C) Ethyne
  D) Ethane
  Show Answer
  The correct answer is A .
• Question 314:

  To what temperature must a gas at 273k be heated in order to double both its volume and pressure?

  Options:
  A) 298K
  B) 546K
  C) 819K
  D) 1092K
  Show Answer
  The correct answer is D .
• Question 315: Which of the following molecules has two other positional isomers? Options:
  A) CH₃CH₂Br
  B) CH₃CHBrCH₃
  C) CBr₂F₂
  D) CH₂CHBrCH₂Br
  Show Answer
  The correct answer is D .
• Question 316:

  When anhydrous cobalt chloride paper is exposed to water, what color change is observed?

  Options:
  A) From pink to blue
  B) From white to blue
  C) From blue to white
  D) From blue to pink
  Show Answer
  The correct answer is D .
• Question 317: A primary amide is generally represented by the formula Options:
  A) RCOOR
  B) RCONH ₂
  C) RCONHR
  D) RCONR ₂
  Show Answer
  The correct answer is B .
• Question 318: 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 319: Gunpower is made from charcoal, sulphur and potassium trioxonitrate (V) The salt in the mixture performs the function of Options:
  A) an oxidant
  B) a reductant
  C) a solvent
  D) a catalyst
  Show Answer
  The correct answer is A .
• Question 320:

  10.0 dm³ of air containing H₂S as an impurity was passed through a solution of Pb(NO₃)₂ until all the H₂S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO₃)₂ + H₂S → PbS + 2HNO₃ the percentage by volume of hydrogen sulphide in the air is?

  (Pb = 207, S = 32, GMV at s.t.p = 22.4dm³)

  Options:
  A) 50.2
  B) 47.0
  C) 4.70
  D) 0.47
  Show Answer
  The correct answer is C .