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 431:

  Which of the following pollutants will lead to the depletion of ozone layer?

  Options:
  A) chlorofluorocarbon
  B) carbon (ii) oxide
  C) hydrogen sulphide
  D) sulphur (iv) oxide
  Show Answer
  The correct answer is A .
• Question 432: 50 cm³ of carbon (II) oxide was exploded with 150 cm³ of air containing 20% oxygen by volume. Which of the reactants was in excess? Options:
  A) Carbon (II) oxide
  B) Carbon (IV) oxide
  C) Oxygen
  D) Nitrogen
  Show Answer
  The correct answer is C .
• Question 433: A gas that turns a filter paper previously soaked in lead ethanoate solution black is? Options:
  A) hyrogen chloride
  B) hydrogen sulphide
  C) sulphur (IV) oxide
  D) sulphur (VI) oxide
  Show Answer
  The correct answer is B .
• Question 434: PCL5(g)= PCL3(g) + Cl2(g)In the reaction above, a decrease in pressure will Options:
  A) Decelerate the reaction
  B) Increase yield of Pcl3
  C) Increase the yield of Pcl5
  D) Accurate the reaction
  Show Answer
  The correct answer is B .
• Question 435: 30cm³ of oxygen at 10 atmospheres pressure is placed in a 20 dm³ container. Calculate the new pressure if temperature is kept constant? Options:
  A) 6.7 atm
  B) 15.0 atm
  C) 60.0 atm
  D) 66. 0 atm
  Show Answer
  The correct answer is B .
• Question 436: When copper powder is heated with concentrated sulphuric acid, the gas produced is? Options:
  A) hydrogen sulphide
  B) sulphur dioxide
  C) sulphur trioxide
  D) hydrogen pentasulphide
  E) sulphur pentoxide
  Show Answer
  The correct answer is B .
• Question 437: In which order are the following salts sensitive to light? Options:
  A) Agl > AgCl > AgBr
  B) AgCl > Agl > AgBr
  C) AgBr > AgCl > Agl
  D) AgCl > AgBr > Agl
  Show Answer
  The correct answer is D .
• Question 438: The solubility curve shows the variation of solute concentration with Options:
  A) volume
  B) temperature
  C) vapour density
  D) pressure
  Show Answer
  The correct answer is B .
• Question 439: When sodium trioxocarbonate (IV) decahydrate loses its water of crystallization to the atmosphere, the process is Options:
  A) deliquescence
  B) efflorescence
  C) hygroscopic
  D) effervesecence
  Show Answer
  The correct answer is B .
• Question 440: If 24.83 cm³ of 0.15 M NaOH is titrated to its end point with 39.45 cm³ of HCl, what is the molarity of the HCl? Options:
  A) 0.094 M
  B) 0.150 M
  C) 0.940 M
  D) 1.500 M
  Show Answer
  The correct answer is A .