Answer :
The ration of the rms speed of 235uf6 to that of 238uf6 is 1.004.
The molecular mass of 235uf6 is 349, while that of 238uf6 is 352.
The rms speed is calculated as
v=√(3RT/m)
Thus the ratio rms speed of 235uf6 to 238uf6 is calculated as
r=√(352/349)=1.004