The radius of the first orbit of H-atom is r. then the radius of the first orbit of `Li^(2+)` will be:

Options

A. r/9
B. r/3
C. 3r
D. 9r

Answer

B

Explanation

Formula for radius of H-like species,
`r_(n)=0.529xxn^(2)/ZÅ`
As `0.529xxn^(2)` is radius for H atom which is equal to r (given)
So, `r_(n)=r/3(n=1,Z=3,"for "Li^(2+))`.