Which of the following does not possess a permanent dipole moment?

Explain why $O=C=O$ is non-polar while $R-O-R$ is polar?

Determine the correct sequence of polarity for the following molecules:
$(1)$ Benzene
$(2)$ Inorganic Benzene $(B_3N_3H_6)$
$(3)$ $PCl_3F_2$
$(4)$ $PCl_2F_3$
(Where $P = \text{polar}$,$NP = \text{non-polar}$)

The standard molar enthalpy of vaporisation $(\Delta_{vap}H^{\circ})$ of $A, B$ and $C$ liquids is $23.3, 41$ and $29 \ kJ \ mol^{-1}$ respectively. The correct order of dipole-dipole attractive forces in these liquids is

$A$ diatomic molecule has a dipole moment of $1.2 \, D$. If its bond length is equal to $10^{-10} \, m$,then the fraction of an electronic charge on each atom will be .............. $\%$

The pair from the following pairs having both compounds with net non-zero dipole moment is