What is the root mean square speed of argon

gas at 300 K?
1. 4.33 × 102 m/s
2. 1.37 × 101 m/s
3. 3.96 × 102 m/s
4. 4.30 × 101 m/s
5. 5.92 × 102 m/s

1 answer

Isn't that v(rms) = sqrt (3RT/M)
M is the molar mass in Kg.