Question

What is the number of molecules present in $5$ liters of carbon dioxide at $STP$?

• A. $6.022\times {10}^{23}$ molecules
• B. $1.344\times {10}^{23}$ molecules
• C. $6.022\times {10}^{20}$ molecules
• D. $1.344\times {10}^{20}$ molecules

Answer 1

Answer: (B)

$1.344\times {10}^{23}$ molecules

No. of moles $=\frac{Givenvolume}{22.4L}$ (in $L$)
$=\frac{5}{22.4}$
$=0.223$ moles
No. of molecules = No. of moles $\times Na$
$=0.223\times 6.023\times {10}^{23}$
$=1.344\times {10}^{23}$

Hence, Option "B" is the correct answer.