Which of the following has zero dipole moment?

Which of the following molecules has a zero dipole moment?

The unequal sharing of bonded pair of electrons between two atoms in a molecule causes

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

Write the significance/applications of dipole moment.

Arrange the following compounds in the increasing order of their dipole moment.