Question

How many valence electrons does $N{O^ - }_3$ have?

Answer 1

Hint : Valence electrons are the electrons present in the outermost shell. Now in this case it has three oxygen and one nitrogen atom, to find out valency will use octet rule, with the help of this rule valency can be obtained.

Complete Step By Step Answer:
By using octet rule, as we know we have three oxygen and one nitrogen atom,
So we know nitrogen belongs to group $15$ thus, it forms bond with three atoms of oxygen with the charge of $+ 5$
Oxygen as we know belongs to the group $16$ in the periodic table so we know the electrons present in its valence shell are $6$ . And there are a total of three oxygen atoms.
And one more electron of nitrate anion.
So to find out the valency of nitrate ion,
5 + (3 \times 6) + 1 = 5 + 18 + 1 \\\ = 24 \\\

Note :
Nitrate is used in agriculture as a fertilizer and explosive. It has high solubility and biodegradability. Nitrates play a very important role for the human body also. This is also known as a potent oxidising agent.