Which of the following molecules shows the least dipole moment?

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 ...... .

What is the increasing order of dipole moment for the following compounds? $(i)$ Toluene $(ii)$ $m$-dichlorobenzene $(iii)$ $o$-dichlorobenzene $(iv)$ $p$-dichlorobenzene

Consider the following:
Assertion $(A)$: Dipole moment of $NF_3$ is lesser than $NH_3$.
Reason $(R)$: In $NF_3$,the orbital dipole due to lone pair of electrons is in the opposite direction to the resultant dipole moment of the three $N-F$ bonds.
The correct answer is:

For which molecules among the following,the resultant dipole moment $(\mu) \neq 0?$

The correct order of dipole moment is