Question

Under $3$ atm, $12.5$ litre of a gas weighs $15$ gm. What will be the average speed of gaseous molecules?

• A. $8.028\times {10}^4$ cm/sec
• B. $6.028\times {10}^2$ cm/sec
• C. $8.028\times {10}^5$ cm/sec
• D. $6.028\times {10}^4$ cm/sec

Answer 1

The correct option is A $8.028\times {10}^4$ cm/sec

Given,

Pressure = 3atm

Volume = 12.5 litre

Weight = 15 g

For gas We have $PV=\frac{w}{m}RT$

$⟹3\times 12.5=\frac{15}{m}\times 0.0821\times T$

$T_m=30.45$

Now,

$U_{AV}=\sqrt{\frac{8RT}{\pi m}}$

$=\sqrt{\frac{8\times 8.314\times 107\times 30.4\times 7}{22}}$

$=8.028\times {10}^{4}cmse{c}^{-1}$