Question

A He atom $300K$ is released from the surface of the earth to travel upward. Assuming that it undergoes no collision with other molecule, how high will it be before coming to the rest?

• A. $9.53m$
• B. $95.3m$
• C. $953m$
• D. $9.53\times {10}^{4}m$

Answer 1

Answer: (B)

$95.3m$

$\begin{array}{c}K.E.=\frac{3}{2}RT\\ =\frac{3}{2}\times \frac{1}{N_A}\times 8.314\times 300\\ K.E.=mgh\\ \frac{3}{2}\times nRT=mgh\\ \frac{3}{2}\times \frac{1}{6.022\times {10}^{23}}\times 8.314\times 300=mgh\\ h=95.3m\end{array}$