Chemistry - GOC Question with Solution | TestHub

In methanol the C-O bond is a pure single bond (longest). In phenol the O lone pair delocalises into the ring, which gives partial double-bond character. The para $\mathrm{N}{\mathrm{O}}_2$ group (-M) increases this delocalisation, so it is the shortest in (c). So a $>$ b $>$ c.