Chemistry - GOC Question with Solution | TestHub

The aryl-${\mathrm{NO}}_2$ $\mathrm{C}-\mathrm{N}$ bond is shortened by conjugation when the nitro group can lie near the ring plane. Ortho crowding twists ${\mathrm{NO}}_2$, reducing pi overlap and increasing the $\mathrm{C}-\mathrm{N}$ single-bond character. Bond x is flanked by $\mathrm{I}$ and $\mathrm{Br}$, y by $\mathrm{I}$ and $\mathrm{H}$, and z by $\mathrm{Br}$ and $\mathrm{H}$. With $\mathrm{I}$ more sterically demanding than $\mathrm{Br}$, crowding decreases x > y > z. The qualitative bond-length order is therefore x > y > z, $\mathrm{B}$.