Two molecules of a gas have speeds of 9×106ms-1 and 1×106ms-1, respectively. What is the root mean square speed of these molecules. 

Hint: Use the concept of RMS speed.
Step 1: Write the formula of RMS speed.
For n-molecules, we know that,
vrms=v12+v22+v32+......+vn2n
[vrms=rootmeansquarevelocity]
Where v1,v2,v3.............vn are individual velocities of n-molecules of the gas
Step 2: Find the RMS speed of the gas.
For two molecules,
vrms=v12+v222                    [v1,v2,v3..............vn are individual velocities]
Given,
v1=9×106m/s
v2=1×106m/s
vrms=(9×106)2+(1×106)2
=81×1012+1×10122
=(81+1)×10122
=82×10122
=41×106m/s