Question

The number of atoms of Na in 8 g of its sample is $x\times {10}^{23}$.The value of x( rounded off to the nearest integer) is

[Given : $N_A=6.02\times {10}^{23}mo{l}^{-1}$
and Atomic mass of Na=23.0u]

Answer 1

$1mol$ of $Na$ or $23g$ of $Na$ has $6.02\times {10}^{23}$ atoms.
$8g$ of $Na$ has:
$\frac{8}{23}\times 6.02\times {10}^{23}$ atoms
$\Rightarrow 2.09\times {10}^{23}$ atoms
$\approx 2\times {10}^{23}$ atoms
The value of x is 2