The rms speed of molecules of gas of density 4kg/m? and pressure 12?10?Nm-? is...

The equation for the root-mean-square speed is:

​​​​​​v_rms = $\sqrt{3RT/M_m}$
where,
R is the universal gas constant, 8.314472 J/mol K.
T is the temperature in K.
M_m is the molar mass of the gas in kg/mol.

Ideal gas equation,

PV=nRT
PV/n = RT

Now.
v_rms = $\sqrt{3PV /n{M}_m}$

density = mass /volume
1/ density (ρ) = M/V

=$\sqrt{3P/\rho }$
=$\frac{\sqrt{3 * 1.2 * {10}^{5 }}}{2}$
= 300 m/s