Answer
$v_{rms}=511$ $\frac{m}{s}$
Work Step by Step
We know that
$v_{rms}=\sqrt\frac{3RT}{M}$...eq(1)
First, we convert the temperature to Kelvin:
$T=C^{\circ}+273K=20+273=293K$
We also know that $M=28\times10^{-3}Kgmol^{-1}$.
We then substitute the values of $R,T$ and $M$ in eq(1):
$v_{rms}=\sqrt\frac{3(8.314)(293)}{28\times10^{-3}}$
$v_{rms}=511$ $\frac{m}{s}$
