Answer
Neon
Work Step by Step
We can identify the required gas as follows:
$m=\frac{3p}{(\frac{N}{V})v_{rms}^2}$
We plug in the known values to obtain:
$m=\frac{3\times 2\times 10^5}{4.2\times 10^{25}(660)^2}$
This simplifies to:
$m=3.2\times 10^{-26}Kg$
The value of mass shows that the required gas is Neon.
