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Model Paper 4 — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryModel Paper 43 Marks
Question
Calculate the number of atoms in each of the following
1. 52 mole of Ar
2. 52 u of He
3. 52 g of He .
✓

Answer

1. 1 mole of Ar contains $6.022 \times 10^{23}$ atoms
$\therefore 52$ mole of Ar will contain $6.022 \times 10^{23} \times 52=3.13 \times 10^{25}$ atoms
2. 4 u of $He =1 He$ atom
$\therefore 52 u$ of $He =\frac{1}{4} \times 52 He$ atoms $=13 He$ atoms.
3. 1 mol atom of $He =4 g=6.023 \times 10^{23}$ atoms
4 g of He contains $6.022 \times 10^{23}$ atoms
52 g of He will contain $=\frac{6.022 \times 10^{23} \times 52}{4}=7.83 \times 10^{24}$ atoms.

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