Question

Which of the following elemnts shows a valency of '3' by gaining an electron?

• A. Boron
• B. Nitrogen
• C. Aluminium
• D. Phosphorous

Answer 1

Answer: (B), (D)

The correct options are
B Nitrogen
D Phosphorous

The elements with their electronic configuration and valency are given below:
$$\begin{array}{ccc}\text{Elements}& \text{Electronic configuration}& \text{Valency}\\ \text{Boron}& (2,3)& \text{3}\\ \text{Nitrogen}& (2,5)& \text{3}\\ \text{Aluminium}& (2,8,3)& \text{3}\\ \text{Phosphorous}& (2,8,5)& \text{3}\end{array}$$
From the above table we can see all the elements are having valency of '3'.
Here elements like nitrogen and phosphorous will show a valency of '3' by gaining an electron as its easy for them to gain three electron. While in case of boron and aluminium, they will also a valency of '3' by loosing three electrons, as its easy for them to loose three electrons rather than to gain five electron to complete its octet.