The speed of the electron (in ms^(-1)) in the third orbit of hydrogen atom is approximately (mass of electron `=9.1xx10^(-31)kg`)

Options

A. `3.6xx10^(5)`
B. `2.18xx10^(6)`
C. `7.26xx10^(5)`
D. `2.18xx10^(5)`

Answer

C

Explanation

Velocity of an electron can be given as follows:
Velocity (speed) `[v]= 2.18 xx10^(6) , (Z)/(n)`
where , Z = atomic number
n = number of orbit
For hydrogen atom , ` Z = 1 rArr n = 3 `
Therefore , ` V = 2.18 xx10^(6),(Z)/(n) = 2.18 xx 10^(6) xx (1)/(3)`
` = 0.726 xx 10^(6) ms^(-1)`
` v= 7.26 xx10^(5) ms^(-1)`
Hence , option (c) is the correct answer .