The differnce between nth and `(n+1)` the Bohr radius of B atom is equal to be its `(n-1)` th Bohr radius .The value of n is

Answer

4

Explanation

`:' r_n = n^2 xx r_1`
` r_(n+1) = (n+1)^2 xx r_1`
` r_(n+1) = (n+1)^2 xx r_1`
`r_(n+1) -r_n =r_(n-1)`
`:. (n+1)^2r_1 - n^2 r_1 = (n-2)^3 r_1` ltbRgt ` :. [n^2 +2n+1] - n^2 = [n^2 -2n + 1]` ltbRgt or ` n^2 - 4n =0 :. N=4` .