At what temperature will oxygen molecules have the same root mean square speed as hydrogen molecules at 200 K?
527°C
1327°C
2127°C
2927°C
For oxygen:
vrms=3kT0m0
For hydrogen:
vrms=3kThmh
The value of vrms will be the same if
T0m0=Thmhor T0=m0mh×Th=16×200 =3200K=2927∘C
Hence the correct choice is (4).