Which of the following molecules shows the least dipole moment?

Which carbonyl compound has the maximum dipole moment?

If the $HCl$ molecule were completely polar,the expected dipole moment would be $6.12 \ D$,but the experimental value of the dipole moment is $1.03 \ D$. What is the percentage of ionic character (in $\%$)?

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 pair of molecules are polar species?

Which of the following molecules does not possess a permanent dipole moment?