The geometry and dipole moment of $H_2S$ respectively are

The molecule with non-zero dipole moment is

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

Which of the following molecules will have polar bonds but zero dipole moment?

Which has a permanent dipole moment?

Explain dipole-dipole forces and their characteristics.