In \(\rm NO^-_3\) ion, the number of bond pairs and lone pairs of electrons on nitrogen atom are

Concept: 

• A pair of electrons present in the valence orbital of the atom, which is not involved in the bonding, is lone pair of electrons.
• The two electrons involved in the bonding, form the bond pair of electrons.
• Nitrogen and oxygen both are p-block elements of 2nd period. According to periodic trends, electronegativity increases from left to right across a period.

Explanation:

• To calculate lone pairs and bond pairs, first identify the central atom.
• Generally, the central atom is always the one that is less electronegative. Here, the electronegativity of N is less than the electronegativity of O. Therefore, nitrogen is the central atom.
• In the question we are asked to find lone pairs and bond pairs of N only.

Structure of NO^-₃ is:     

Therefore, NO₃^- have Square planar geometry.

Conclusion:

• Here, 3 sigma bonds + 1 Pi bond = 4 bond pairs.
• There is no any lone pair on the Nitrogen therefore, 0 lone pair.