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Q.
If $19$ is the atomic number of an element, then this element will be
AMUAMU 2002
Solution:
The electronic configuration of the element (atomic number $19$) is as
$1 s^{2}, 2 s^{2} 2 p^{6}, 3 s^{2} 3 p^{6}, 4 s^{1}$
This element is placed in IA group.
So, it is a alkali metal and this element is potassium $(K)$.
It has one electron in its outermost shell.
So, it can loose one electron easily and form positive
ion hence, it is a metal and its oxidation number is $+1$.