Which of the following compounds has zero dipole moment?

Arrange the following compounds in increasing order of their dipole moment :
$HBr$,$H_2S$,$NF_3$ and $CHCl_3$

Which of the following molecules has the maximum dipole moment?

Which compound exhibits the maximum dipole moment among the following?

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 statements regarding $NH_3$ and $NF_3$ is correct?