The first excited state of hydrogen atom is `10.2 eV` above its ground state. The temperature is needed to excite hydrogen atoms to first excited level is

Options

A. `3.8xx10^4 K`
B. `5.2xx10^4 K`
C. `7.9xx10^4 K`
D. `11xx10^4 K`

Answer

C

Explanation

According to kinetic theory of gases,
`K.E. = 1/2mv^2 = 3/2KT`
`therefore "In this case " , E = 10.2 eV = 10.2 xx 1.6 xx10^(-19) J`
`therefore 10.2xx1.6xx10^(-19)= 3/2xx1.38xx10^(-23) xxT`
`therefore T= (2xx10.2xx1.6xx10^4)/(3xx1.38) = 7.9 xx10^4 K`