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 451: 60cm³ of hydrogen are sparked with 20cm³ of oxygen at 100^oC and 1 atmosphere . The total volume of the residual gases in Options:
  A) 60 cm³
  B) 10 cm³
  C) 40 cm³
  D) 30 cm³
  E) 70 cm³
  Show Answer
  The correct answer is A .
• Question 452:

  Crude petroleum is converted to useful products by the processof?

  Options:
  A) fractional crystallization
  B) fractional distillation
  C) filtration
  D) chromatography
  Show Answer
  The correct answer is B .
• Question 453: During a titration experiment, 0.05 moles of carbon (lV) oxide is liberated. What is the volume of gas liberated? Options:
  A) 22.40 dm ³
  B) 11.20 dm ³
  C) 2.24 dm ³
  D) 1.12 dm ³
  Show Answer
  The correct answer is D .
• Question 454:

  What is the chemical structure of soap and detergent molecules?

  Options:
  A) Hydrophilic head and hydrophobic tail
  B) Hydrophilic head and hydrophilic tail
  C) Hydrophobic head and hydrophobic tail
  D) Hydrophilic tail and hydrophobic head
  Show Answer
  The correct answer is A .
• Question 455:

  2SO_2(g) + O_2(g) $⟺$2SO_3(g)

  $△H=-395.7kJmo{l}^{-1}$

  In the reaction above, the concentration of 2SO_3(g) can be in creased by

  Options:
  A) decreasing the pressure
  B) decreasing the temperature
  C) the addition of catalyst
  D) increasing the temperature
  Show Answer
  The correct answer is B .
• Question 456: Sugar is separated from its impurities by Options:
  A) precipitation
  B) crystallization
  C) distillation
  D) evaporation
  Show Answer
  The correct answer is B .
• Question 457: 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 458: The weakest attractive force that can be observed between two molecules is Options:
  A) ionic
  B) covalent
  C) coordinate covalent
  D) van der Waals
  Show Answer
  The correct answer is D .
• Question 459:

  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 460:

  An element X has 127 neutrons and 82 electrons.

  Its atomic number is?

  Options:
  A) 209
  B) 105
  C) 45
  D) 82
  Show Answer
  The correct answer is D .