Amongst $BeF_{2}$,$BF_{3}$,$H_{2}O$,$NH_{3}$,$CCl_{4}$ and $HCl$,the number of molecules with non-zero net dipole moment is ...... .

The dipole moments of the given compounds are:

Which of the following molecules is polar?

Which of the following is a polar compound?

Which of the following has the maximum dipole moment?

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.