Chemistry - GOC Question with Solution | TestHub

Conjugation with $\mathrm{C}=\mathrm{C}$ moves electron density from $\mathrm{C}=\mathrm{O}$ to the $\mathrm{C}=\mathrm{C}$ ($\mathrm{C}=\mathrm{O}$ becomes more single-bond like), which lengthens it. Divinyl ketone (c) has two vinyl groups, acrolein (b) has one and acetone (a) has none. So c $>$ b $>$ a.