How many times the normal electrons of hydrogen atom revolve round the nucleus in on sec ?

Explanation

Number of revolutions `= ("velocity of the electron")/("circumference of shell")`
For hydrogen electron in n = 1, Velocity `= 2.18 xx 10^(6) ms^(-1)`
Circumference of shell `= 2pi r`
`= 2pi xx 0.529 xx 10^(-10) xx n^(2)m`
`= 2xx 3.14 xx 0.529 xx 10^(-10) xx 1^(2)`
`= 3.33 xx 10^(-10) m`
Number of times the electrons revolve in one sec `= (2.18 xx 10^(6))/(3.33 xx 10^(-10)) = 6.55 xx 10^(15) s^(-1)`.