In two individual hydrogen atoms electrons move around the nucleus in circular orbits of radii R and 4R. The ratio of the time taken by them to complete one revolution is:

Options

A. `1 :4`
B. ` 4 :1`
C. ` 1: 8`
D. `8 :`7

Answer

C

Explanation

` T= ( 2 pi r_n)/(u_n) = ( 2 pi _1 xx n^2)/( n_1 //n) ( therefore r_(n) = n^(2)xx r_(1))`
or `T prop n^(3)`,
`therefore T_(1) /T_(2) = 1_(3)/( n^(3)) = (1)/(8)(n=2)`.