How many of the following specific chemical compounds exhibit a strictly non-zero net dipole moment — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

trans-1,2-dichloroethene has opposing dipoles that cancel ($\mu=0$). cis-1,2-dichloroethene has additive dipoles ($\mu eq 0$). Benzene-1,4-diol has non-linear $-OH$ bonds that freely rotate, preventing perfect cancellation ($\mu eq 0$). p-Dichlorobenzene has strictly linear, opposing $C-Cl$ dipoles ($\mu=0$). trans-2-butene has symmetric methyl groups ($\mu=0$). Thus, only exactly 2 compounds possess a non-zero dipole moment.