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Sunday, 21 June 2026
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Chemistry Past Questions and Answers

Topic: The mole concept and Avogadro's number

Jamb Chemistry Questions - The mole concept and Avogadro's number

Question 11:
The density of a certain gas is 1.98gdm-3 at s.t.p. What is the molecular mas of the gas?
  • A 44.0 g
  • B 54.0 g
  • C 26.0 g
  • D 31.0 g
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Question 12:
The volume of 2.5 moles of oxygen at s.t.p is
[Molar volume of a gas at s.t.p = 22.4 dm3]
  • A 50.0 dm<sup style='font-size: smaller;'>3</sup>
  • B 84.0 dm<sup style='font-size: smaller;'>3</sup>
  • C 28.0 dm<sup style='font-size: smaller;'>3</sup>
  • D 56.0 dm<sup style='font-size: smaller;'>3</sup>
View Answer & Explanation
Question 13:
What is the molar mass of a substance, if 0.4 mole of the substance has a mass of 25.0g?
  • A 62.5 g
  • B 40.0 g
  • C 6.3 g
  • D 2.5 g
View Answer & Explanation
Question 14:
Calculate the mass of chlorine gas which occupies a volume of 1.12dm3 at s.t.p
[Cl = 35.5, molar volume of gas at s.t.p = 22.4 dm3
  • A 15.50 g
  • B 7.10 g
  • C 3.55 g
  • D 1.80 g
View Answer & Explanation
Question 15:
Which of the following decrease when a given mass of gas is compressed to half its initial volume?
  • A Atomic radius of each
  • B Average intermolecular distance
  • C Frequency of collisions
  • D Number of molecules presents
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