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

Which of the following is the correct order of dipole moment?

If an $AB_3$ molecule (containing four atoms) has a dipole moment of zero and another has a non-zero dipole moment,what does this indicate about their shapes?

Among the following mixtures,in which is dipole-dipole attraction present?

$H_2O$ is dipolar,whereas $BeF_2$ is not. It is because

The dipole moment is zero for the molecule: