Non-zero dipole moments occur when there is an uneven distribution of charge within a molecule. This can be caused by differences in electronegativity between atoms or by the geometry of the molecule. Let's analyze each molecule to determine if it has a non-zero dipole moment.

- CH2CI2 (Dichloromethane): This molecule has a tetrahedral shape with a carbon atom at the center and two chlorine atoms and two hydrogen atoms attached to it. The chlorine atoms are more electronegative than carbon and hydrogen, resulting in a polar bond. The molecule also has a net dipole moment due to the asymmetrical arrangement of the chlorine atoms. Therefore, CH2CI2 has a non-zero dipole moment.

- CH4 (Methane): Methane has a tetrahedral shape with four hydrogen atoms attached to a central carbon atom. The carbon-hydrogen bonds are nonpolar because carbon and hydrogen have similar electronegativities. The molecule is symmetrical, so the dipole moments of the C-H bonds cancel each other out, resulting in a net dipole moment of zero.

- CCI4 (Carbon tetrachloride): Carbon tetrachloride has a tetrahedral shape with four chlorine atoms attached to a central carbon atom. The carbon-chlorine bonds are polar due to the difference in electronegativity. However, the molecule is symmetrical, so the dipole moments of the C-Cl bonds cancel each other out, resulting in a net dipole moment of zero.

- H2O (Water): Water has a bent or V-shaped molecular geometry with two hydrogen atoms and two lone pairs of electrons surrounding an oxygen atom. The oxygen-hydrogen bonds are polar due to the difference in electronegativity. The molecule is asymmetrical, so the dipole moments of the O-H bonds do not cancel each other out, resulting in a net dipole moment. Therefore, H2O has a non-zero dipole moment.

- CHCI3 (Chloroform): Chloroform has a tetrahedral shape with a carbon atom at the center and three chlorine atoms and one hydrogen atom attached to it. The chlorine atoms are more electronegative than carbon and hydrogen, resulting in polar bonds. The molecule also has a net dipole moment due to the asymmetrical arrangement of the chlorine atoms. Therefore, CHCI3 has a non-zero dipole moment.

- p-dichloro benzene: p-Dichlorobenzene has a planar molecular geometry with two chlorine atoms attached to a benzene ring in opposite positions. The chlorine atoms are more electronegative than carbon, resulting in polar bonds. However, the molecule is symmetrical, so the dipole moments of the C-Cl bonds cancel each other out, resulting in a net dipole moment of zero.

- o-cresol: o-Cresol has a hydroxyl group (-OH) attached to a benzene ring. The oxygen atom is more electronegative than carbon and hydrogen, resulting in a polar bond. The molecule is asymmetrical, so the dipole moment of the O-H bond does not cancel out with the benzene ring, resulting in a net dipole moment. Therefore, o-cresol has a non-zero dipole moment.

- p-xylene: p-Xylene has a planar molecular geometry with two methyl groups (-