Question

$52u$ of $He$ contains:

• A. $(4\times 6.023\times {10}^{23})$ atom
• B. $13$ atoms
• C. $(13\times 6.023\times {10}^{23})$ atoms
• D. $4$ atoms

Answer 1

The correct option is C $(13\times 6.023\times {10}^{23})$ atoms

Molar mass of $He=4u$

Given mass of $He=52u$

Moles of $He=\frac{52}{4}=13\text{mol}$

Since $1$ mole of $He$ contains $6.023\times {10}^{23}$ atoms.

$\therefore$ No. of atoms in $52u$ of $He=13\times 6.023\times {10}^{23}$ atoms.