Which of the following molecules has a zero dipole moment?

Give the correct order of initials $T$ or $F$ for the following statements. Use $T$ if the statement is true and $F$ if it is false.
$I. \, (CH_3)_2P(CF_3)_3$ is non-polar and $(CH_3)_3P(CF_3)_2$ is a polar molecule.
$II. \, CH_3 \widehat{P} CH_3$ bond angles are equal in the $(CH_3)_3P(CF_3)_2$ molecule.
$III. \, PF_3$ will be more soluble in a polar solvent than $SiF_4$.

Which has zero dipole moment?

Which of the following exhibits a dipole moment?

Which one of the following molecules is polar?

One Debye is equal to how many coulomb meter?