Hi,
rms velocity ofM2at11TP=V1=1.84km/s

as,V1=root(3RT/M1)(1)
M1=molar mass ofH2=0.002kg/moL

and that of oxygen(O2)

V2=root (3RT/M2)(2)
M2=0.032kg/moL

so dividing(1)(2),

V1/V2 = root(M2/M1)
V2=V1 root(M1/M2)

V2=1.84 x root(2/32)
V2= 0.46km/s

V2=1.84322=1.8441=0.46km/s