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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 26:
A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.
[H = 1, C = 12, O = 16]
  • A C\(_3\)H\(_6\)O\(_3\)
  • B C\(_6\)H\(_6\)O\(_3\)
  • C C\(_6\)H\(_{12}\)O\(_6\)
  • D CH\(_2\)O
View Answer & Explanation
Question 27:
The velocity, V of a gas is related to its mass, M by (k = proportionality constant)
  • A V = \(\frac{k}{M}\)
  • B V = \(\frac{k}{M^{\frac{1}{2}}}\)
  • C V = \(kM^2\)
  • D V = \((\frac{k}{M})^{\frac{1}{2}}\)
View Answer & Explanation
Question 28:
The volume occupied by 1.58g of a gas at S.T.P is 500cm\(^3\). What is the relative molecular mass of the gas? [ G.M.V at S.T.P = 22.4dm\(^{3}\) ]
  • A 28
  • B 32
  • C 44
  • D 71
View Answer & Explanation
Question 29:
If the volume of a given mass of a gas at 0ºc is 29.5cm\(^3\). What will be the volume of the gas at 15ºc, given that the pressure remains constant.
  • A 31.6
  • B 62.2
  • C 32.7
  • D 31.1
View Answer & Explanation
Question 30:
What is the molar mass of water (H2O)?
  • A 18 g/mol
  • B 22 g/mol
  • C 16 g/mol
  • D 12 g/mol
View Answer & Explanation