Which of the following is a polar compound?

Which one of the following molecules has a zero dipole moment?

Which of the following molecules possesses a permanent dipole moment?

Which bond angle $\theta$ would result in the maximum dipole moment for the triatomic molecule $XY_2$ shown below?

The compound that will have a permanent dipole moment among the following is

Given below are two statements:
Statement-$I$: Since fluorine is more electronegative than nitrogen,the net dipole moment of $NF_3$ is greater than $NH_3$.
Statement-$II$: In $NH_3$,the orbital dipole due to lone pair and the dipole moment of $N-H$ bonds are in opposite direction,but in $NF_3$ the orbital dipole due to lone pair and dipole moments of $N-F$ bonds are in same direction.
In the light of the above statements,choose the most appropriate from the options given below.