Question

If a molecule $M{X}_3$ has zero dipole moment, the sigma bonding orbitals used by $M$ (atomic number $<21$) are:

• A. pure $p$
• B. $sp$ hybrid
• C. $s{p}^2$ hybrid
• D. $s{p}^3$ hybrid

Answer 1

Answer: (C)

$s{p}^2$ hybrid

If dipole moment is zero in ${MX}_3$, then the bond angle is $120°$. There should be no lone pair on central atom and $3$ bounds surrounded to it. One ${}^{\prime }{s}^{\prime }$ and $2^{\prime }{p}^{\prime }$ orbitals are included. So hybridisation is ${sp}^2$.

Example, ${BF}_3$.