The correct option is
A True
Formula for Velocity of Sound in a Gas is;
v=(γRT/M)1/2, where
γ is adiabatic index of gas,
R and
T are universal gas constant and temperature of gas and
M is the molecular weight of gas.
Now, γo=7/5 and of γhe=5/3
Also, Mo=32 and that of MHe=4
so, byputting known values in velocity formula we get;
Velocity of sound in Oxygen is less than in Helium.
Hence, the given statement is True