Question

At $1520$ $mm$ pressure and ${273}^{o}C$, the number of molecules present in $5.6$ litres of a gas is:

• A. $6\times {10}^{23}$
• B. $\frac{6\times {10}^{23}}{4}$
• C. $\frac{6\times {10}^{23}}{16}$
• D. $\frac{6\times {10}^{23}}{20}$

Answer 1

Answer: (B)

$\frac{6\times {10}^{23}}{4}$

Given,
Pressure $=1520$ $mm$ $=2$ $atm$.
Temperature $={273}^{o}C$ $=546$ $K$.
At $1520$ $mm$ pressure and ${273}^{o}C$,
number of moles $\left(n\right)$ $=\frac{PV}{RT}=\frac{2\times 5.6}{0.0821\times 546}=1:4$ (Ideal Gas Equation)
$1$ mole contains $6.023\times {10}^{23}$ molecules of it.
Thus, $\frac{1}{4}$ moles of it contains $\frac{6.023\times {10}^{23}}{4}$ molecules.