Question

The average molecular speed is the greatest in which of the following gas samples?

• A. of at
• B. of at
• C. of at
• D. of at

Answer 1

The correct option is D

of at

$u\left(av\right)$ = $\sqrt{\frac{8RT}{\pi M}}$

$u\left(av\right)$ $\propto \sqrt{\frac{T}{M}}$

But independent of number of moles

$u\left(O_2\right)\propto \sqrt{\frac{560}{32}}=4.18$

$u\left(Ne\right)\propto \sqrt{\frac{500}{20}}=5.0$

$u\left(C{O}_2\right)\propto \sqrt{\frac{440}{44}}=3.16$

$u\left(He\right)\propto \sqrt{\frac{140}{4}}=5.92$