An assembly of smoke particle in air at `NTP` is under consideration. If the mass of each particles is `5 xx 10^(-17) kg`. Then the rms speed is
(Given: `k = 1.38 xx 19^(-23) J K^(-1)`)

Options

A. `1.5 cm s^(-1)`
B. `1.5 mm s^(-1)`
C. `1.5 m s^(-1)`
D. `1.5 km s^(-1)`

Answer

A

Explanation

`1/2 mC^(2) = 3/2 kT, C = sqrt((3kT)/(m))`
`=sqrt((3xx1.38xx 10^(-23)xx 273)/(5xx10^(-17)))`
`=15xx10^(-3) ms^(-1) = 1.5cms^(-1)`.