If the rms speed of nitrogen at a certain temperature is 3000 `ms^(-1)`, the approximate kinetic energy of one mole of nitrogen at that temperature in kJ is :

Options

A. `9.0`
B. `126.0`
C. `90.0`
D. `12.6`

Answer

B

Explanation

`v_(rms) = sqrt((2E)/(m))`
`3000 = sqrt((2E)/(28 xx 10^(-3)))`
`E = (9 xx 10^(6) xx 28 xx 10^(-3))/(2)`
`= 126 xx 10^(3) J mol^(-1)`
`= 126 kJ mol^(-1)`