At what temperature of oxygen molecules have the same rms velocity as helium molecules at N.T.P.? (Molecular wt. of oxygen is 32 and that of helium is 4).

Options

A. `1900^(@)C`
B. `1911^(@)C`
C. `1950^(@)C`
D. `1970^(@)C `

Answer

B

Explanation

`(C_(2))/(C_(1))=sqrt((M_(1))/(M_(2))xx(T_(2))/(T_(1)))`
`1=(M_(1))/(M_(2))xx(T_(2))/(T_(1))`
`therefore T_(2)=(M_(2))/(M_(1))xxT`
`=(32)/(4)xx273`
`T=8xx273=2184`
`t=2184-273=1911^(@)C`