Question

The number of oxygen atoms in $4.4\, g$ of $CO_2$ is,

• A. $1.2 \times 10^{23}$
• B. $6 \times 10^{22}$
• C. $6\times 10^{23}$
• D. $12 \times 10^{23}$

Answer 1

Answer: (A)

$1.2 \times 10^{23}$

Answer 2

Molar mass of $CO _{2}=12+32=44$
$\because \frac{W}{M} =\frac{N}{N_{A}}$ (for $CO _{2})$
$\frac{4.4}{44} =\frac{N}{6 \times 10^{23}}$
$\therefore \, N =\frac{4.4 \times 6 \times 10^{23}}{44}$
$=0.1 \times 6 \times 10^{23}=6 \times 10^{22}$
$N=2$ times of $6 \times 10^{22}$
$(\because$ Each $CO _{2}$ contains two oxygen atoms)

$\therefore N$ (oxygen) $=2 \times 6 \times 10^{22}$
$=1.2 \times 10^{23}$