If electron with principal quantum number `n gt 4` were not allowed in nature , the number of possible element would be

Options

A. `(1)/(2) n (n + 1)`
B. `{ (n (n + 1))/(2)}^(2)`
C. `(1)/(6) n (n + 1) (2 n + 1) `
D. `(1)/(3) n (n + 1) (2 n + 1) `

Answer

D

Explanation

For each principal quantum number `n` number of electrons permitted eqauls the number of element corresponding to the quantum number.
`(("Totl number"),("of element"))= sum `2n^(2) = (n(n + 1) (2n + 1))/(3)`