Question

If ($N$) is a non metal then number of electrons in its valence shell may be:
A.) $1$
B.) $3$
C.) $7$
D.) $2$

Answer 1

The non metals are electronegative in nature and they have the tendency to gain an electron. Similarly, we have to think in the case of $(N)$ that what valency it should have to gain an electron.

Complete step by step answer:
To solve this question first we will discuss some chemical properties of non metals from which we could be able to find valence electrons of nitrogen.
We know that non metals generally have four to eight ($4 - 8$) electrons in their valence shell which helps them to complete their octet by gaining electrons from other elements.
Non- metals generally have higher electronegativity and they are generally good oxidising agents. Due to these properties they have tendency to gain electrons.
For option $- (1)$:
If $(N)$ will have one valence electron in its outer shell then it has to gain seven electrons to complete its octet which is very difficult to get. So, one valence electron is not possible for this non metal.
For option $- (2)$:
If $(N)$ will have three valence electrons in its outer shell then it has to gain five electrons to complete its octet which is also very difficult to get. So, three valence electrons are also not possible for this non metal.
For option $- (3)$:
If $(N)$ will have seven valence electrons in its outer shell then it has to gain only one electron to complete its octet which is very easy to get. So, a seven valence electron is possible for this non metal.
For option $- (4)$:
If $(N)$ will have two valence electrons in its outer shell then it has to gain six more electrons to complete its octet which is very difficult in this case also. So, two valence electrons are not possible for this non metal.
So, we can conclude that if this non metal will have seven valence electrons then it can complete its octet very easily by gaining an electron.
Hence, option C.) is the correct answer.

Note:
Remember that a non metal is that substance which can gain electrons very easily. They do so generally to complete their octet and It will be difficult for them to gain electrons more than two or three.