The temperature at which the `rms` speed of air molecules is double of that at `STP` is

Options

A. `819^(@)C`
B. `719^(@)C`
C. `909^(@)C`
D. None of these

Answer

A

Explanation

`v_(rms) prop sqrt(T)`
`implies (v_(1))/(v_(2))=(T_(1))/(T_(2))`
`implies (v^(2))/(4v^(2))=(273)/(T_(2))`
`implies T_(2)=1092 K`
`=819^(@)C`