Which of the following are arranged in the decreasing order of dipole moment?

Which one of the following molecules is polar?

Assertion : Molecules of larger size have higher polarizability.
Reason : Polarizability is observed only in those molecules which have a permanent dipole moment.

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 cyanide ion $(CN^{-})$ and $N_2$ are isoelectronic. However,in contrast to $CN^{-}$,the $N_2$ molecule is chemically inert due to:

Which of the following bonds is the most polar?