At what temperature is the "effective" speed of gaseous hydrogen molecules (molecular weight = 2) equal to that of oxygen molecules (molecular weight = 32) at `47^@ C`?

Answer

B, C

Explanation

`v_(rms)= sqrt((3 R T)/(M)) prop sqrt((T)/(M))`
`v_(rms)` is same. Hence,
`((T)/M)_(H 2) = ((T)/(M))_(O 2)`
or `T_(H 2) = (M_(H 2)/(M_(O 2))) T_(O2)`
`= (2/(32)) (273 + 47)`
`= 20 K = - 253^@ C`.