Which one is a polar molecule among the following?

The $ICl$ molecule is

Both $BF_3$ and $NH_3$ are covalent molecules. However,$BF_3$ is non-polar while $NH_3$ is polar. What is the reason for this?

Which of the following molecules have non-zero dipole moments?
$I$. Gauche conformation of $1, 2$-dibromoethane
$II$. Anti conformation of $1, 2$-dibromoethane
$III$. Trans-$1, 4$-dibromocyclohexane
$IV$. Cis-$1, 4$-dibromocyclohexane
$V$. Tetrabromomethane
$VI$. $1, 1$-dibromocyclohexane

The correct order of dipole moment is:

Which molecule does not show zero dipole moment?