Question

The volume of a gas at $0^{\circ }C$ and $700mm$ pressure is $760cc$. The no. of molecules present in this volume is_____________.

• A. $1.88\times {10}^{22}$
• B. $6.022\times {10}^{23}$
• C. $18.8\times {10}^{23}$
• D. $18.8\times {10}^{22}$

Answer 1

Answer: (A)

$1.88\times {10}^{22}$

Formula,

$PV=nRT$

Given,

$P=700mm=0.921atm$

$V=760cc=0.76L$

$R=0.0821Latm{K}^{-1}mo{l}^{-1}$

$T=0^{\circ }C=273K$

$\Rightarrow n=\frac{PV}{RT}$

$=\frac{0.921\times 0.76}{0.0821\times 273}$

$\therefore n=0.0312moles$

Number of moles,

$=0.0312moles\times 6.023\times {10}^{23}$

$=1.88\times {10}^{23}$ molecules

Hence the correct option is A.