Answer
The gas is $N_{2}$
Work Step by Step
$N_{2}$ has molar mass $28g$ and $V_{rms}=517m/s$ which is same as we obtained.
So, from the molar mass and $V_{rms}$, this gas can be identified as $N_{2}$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.