At $STP$,$0.5 \ mol$ of $H_2$ gas and $1 \ mol$ of $He$ gas:

If $N_2, O_2, H_2$,and $He$ are filled separately in four car tubes at the same pressure,which gas will fill first?

Which of the following statements is true about an ideal gas?

An ideal gas cannot be liquefied because

Two gases $A$ and $B$ are released from the two ends of a tunnel of length $100 \ m$. $A$ travels $40 \ m$ before meeting the gas $B$ in the tunnel. If the molecular weight of $B$ is $18$, what is the molecular weight of $A$ (in $.5$)?

Kinetic energy of molecules is highest in