Identify the non-polar molecule in the set of compounds given: $HCl, HF, H_2, HBr$.

Identify the incorrect statement $:-$

Which one of the following arrangements of molecules is correct on the basis of their dipole moments?

The dipole moment of chlorobenzene is $1.73 \, D$. The dipole moment of $p-$dichlorobenzene is expected to be $............ \, D$.

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.

Which molecule is polar?