* Valency refers to the combining power of an element, which is determined by the number of electrons an atom can gain, lose, or share to form a chemical bond.
* Oxygen (O) usually has a valency of 2.
* In NO₂ (Nitrogen dioxide), there are two oxygen atoms, each with a valency of 2, giving a total valency of 4 for oxygen.
* Since the molecule is neutral, the valency of nitrogen must be 4 to balance the valency of the two oxygen atoms.
Therefore, the valency of N in NO₂ is 4.
