MHTCET 10 May 2024 Shift 2 Paper

Concept:Resonance structures of $\mathrm{NO}_2^-$ are counted by the possible positions of the double bond.Explanation:Total valence electrons in $\mathrm{NO}_2^-$: $5 + 2(6) + 1 = 18$.The skeletal structure is $\mathrm{O-N-O}$.Nitrogen forms one double bond and one single bond with the two oxygen atoms.This double bond can be placed with either of the two oxygen atoms.So there are two equivalent resonance structures for $\mathrm{NO}_2^-$.Answer:The number of Lewis structures is $2$.Correct option: B.