Which molecule has both non-polar and polar bonds,but the molecule as a whole is polar?

Which of the following molecules exhibits the lowest dipole moment?

Which of the following molecules exhibits a dipole moment?

Explain the dipole moment of $AB_2$ linear molecules (e.g.,$BeF_2$) and $AB_2$ angular molecules (e.g.,$H_2O$).

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

Which of the following is a polar molecule?