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 191:

  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 .
• Question 192: The hydrocarbon used in the production of styrene is Options:
  A) ethyne
  B) propyne
  C) ethane
  D) ethene
  Show Answer
  The correct answer is D .
• Question 193:

  Which noble gas is radioactive and is produced as a decay product of uranium and thorium?

  Options:
  A) Argon
  B) Krypton
  C) Radon
  D) Neon
  Show Answer
  The correct answer is C .
• Question 194:

  A dense white fume is formed when ammonia gas reacts with

  Options:
  A) O_2(g)
  B) H_2(g)
  C) Cl_2(g)
  D) HCl_(g)
  Show Answer
  The correct answer is D .
• Question 195:

  On which of the following is the solubility of a gaseous substance dependent? 

  I. Nature of solvent 

  II. Nature of solute 

  III. Temperature 

  IV. Pressure

  Options:
  A) I, II, III and IV
  B) I and II only
  C) II only
  D) I, III and IV only
  Show Answer
  The correct answer is D .
• Question 196:

  

  The compound above is the product of the oxidation of

  Options:
  A) 2-methlbutan-2-ol
  B) 2-methylbutan -1- ol
  C) 2, 3-dimethylprop 1-ol
  D) Pentan -2- ol
  Show Answer
  The correct answer is B .
• Question 197: Calculate the amount in moles of a gas which occupies 10.5 dm³ at 6 atm and 30^oC [R = 082 atm dm³ K^-1 mol^-1] Options:
  A) 2.536
  B) 1.623
  C) 4.736
  D) 0.394
  Show Answer
  The correct answer is A .
• Question 198: The air around smelting industries is likely to contain Options:
  A) H₂S, CO and N₂
  B) CO₂, SO₃ and H₂
  C) H₂, SO₂ and CO₂
  D) SO₂, N₂ and CO₂
  Show Answer
  The correct answer is C .
• Question 199: How much of magnesium is required to react with 260cm³ of 0.5 M HCl? [Mg = 24] Options:
  A) 0.3g
  B) 1.5g
  C) 2.4g
  D) 3.0g
  Show Answer
  The correct answer is B .
• Question 200:

  What is the concentration of a solution containing 2g of NaOH in 100cm³ of solution?

  [Na=23, O=16, H=1]

  Options:
  A) 0.05 moldm^-3
  B) 0.30 moldm^-3
  C) 0.50 moldm^-3
  D) 0.40 moldm^-3
  Show Answer
  The correct answer is C .