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 871:

  220g of carbon dioxide contains ----- moles

  Options:
  A) 5
  B) 6
  C) 3
  D) 4
  Show Answer
  The correct answer is A .
• Question 872: An increase in entropy can best be illustrated by Options:
  A) mixing of gases
  B) freezing of water
  C) the condensation of vapour
  D) solidifying candle wax
  Show Answer
  The correct answer is A .
• Question 873: A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y. Options:
  A) 128
  B) 8
  C) 16
  D) 64
  Show Answer
  The correct answer is A .
• Question 874:

  Two cylinders A and B each contains 30 cm³ of

  Oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?

  Options:
  A) 3.2 g
  B) 6.4 g
  C) 80.0 g
  D) 160.0 g
  Show Answer
  The correct answer is D .
• Question 875: 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 876: The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is Options:
  A) Phosphorus-32
  B) Cobalt-60
  C) Carbon-14
  D) Iodine-131
  Show Answer
  The correct answer is B .
• Question 877: Which of the following is found in cotton Options:
  A) Starch
  B) Cellulose
  C) Fat
  D) Oil
  Show Answer
  The correct answer is B .
• Question 878:

  The oxidation state(s) of nitrogen in ammonium nitrite is/are

  Options:
  A) -3, +3
  B) +5
  C) -3, +5
  D) -3
  Show Answer
  The correct answer is A .
• Question 879:

  Which of the following statements is correct about the periodic table?

  Options:
  A) Elements in the same period have the same number of valence electrons
  B) The valence electrons of the elements in the same period increase progressively across the period
  C) Elements in the same group have the same number of electron shells
  D) The non-metallic Properties of the elements tend to decrease across each period
  Show Answer
  The correct answer is B .
• Question 880: Which of the following conduct electricity? Options:
  A) sulfur
  B) graphite
  C) diamond
  D) red phosphorus
  E) yellow phosphorus
  Show Answer
  The correct answer is B .