Question

If $19$ is the atomic number of an element, then this element will be

• A. a metal with +3 oxidation state
• B. a metal with +1 oxidation state
• C. an inert gas
• D. a metal with -3 oxidation state

Answer 1

Answer: (B)

The electronic configuration of the element (atomic number $19$) is as
$1s^2,2s^{2}2p^6,3s^{2}3p^6,4s^1$
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 $+1$.