Assign the position of the element having outer electronic configuration (1) `ns^(2_np^(4)` for n=3,
(2) `(n-1)d^(2)ns^(2)` for n=4.

Explanation

(1) As n=3, the element belongs to third perriod, since the last electron enters the p-orbital, the given element is a p-block element. For p-blcok elements, group no, of the lemennt=10+no. of electrons in the valence shell.
`therefore` The element is in the (10+6)=16th period.
(2) As n=4, the element belongs to the fourth period. since d-electrons are present in the element, it is a d-block element. for d-block elements, group no. of the element=no. of ns electrons+ no. of (n-1)d electrons =2+2=4. therefore, the element is in the 4th period.