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ICSE Class 10 Chemistry Question 25 of 25

Gay Lussac's Law — Avogadro's Law — Mole Concept — Question 25

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Question 25

State which has higher no. of atoms : 1 g of O2 or 1 g of Cl2 [O = 16, Cl = 35.5]

Answer

Molecular mass of O2 = 2 x 16 = 32 g

32 g of O2 = 2 x 6.023 x 1023 atoms

∴ 1 g of O2

=2×6.023×102332=0.0625×6.023×1023 atoms= \dfrac{2 \times 6.023 \times 10^{23}}{32} \\[0.5em] = 0.0625 \times 6.023 \times 10^{23} \text{ atoms}

Molecular mass of Cl2 = 2 x 35.5 = 71 g

71 g of Cl2 = 2 x 6.023 x 1023 atoms

∴ 1 g of Cl2

=2×6.023×102371=0.0281×6.023×1023 atoms= \dfrac{2 \times 6.023 \times 10^{23}}{71} \\[0.5em] = 0.0281 \times 6.023 \times 10^{23} \text{ atoms}

Hence, 1 g of O2 has more number of atoms.