A cubical box of side 1cm contains helium gas (atomic weight =4) at a pressure of $100N/s^2$.During an abservation time of 1sec,an atom travelling with a root mean square speed parallel to one of the edges of the cube was found to make 500 hits with the wall.Evaluate the temperature of the gas

Question

$\begin{array}{1 1}(A)\;320K\\(B)\;640K\\(C)\;480K\\(D)\;160K\end{array}$