An element 'X' has its electronic configuration of 'K' shell is `(n-5)s^(2)` and it has total number of electrons in its outermost, penultimate and antipenultimate shell are 2,8 and 25 respectively then find out total number of unpaired electrons in element 'X' in their ground state.

Answer

7

Explanation

For K shell `(n-5)s^(2) =1 x^(2)` so value of n is .6.
Electronic configuration of .X.
`1s^(2)`...... `4s^(2) 4p^(6) 4d^(10) 4f^(7)5s^(2) 5p^(2)5d^(0)6s^(2)`
Unpaired electron is 7.