Questions

   1) SO2                  2) CH2Cl2                3) PCl3

How to check the given molecules are polar or non polar :

If the electronegativity of the two bonded atoms are different then the bond is polar. Although, some molecules contain polar bonds, the molecule may be non-polar. If the polarity of all the bonds present in the molecule are cancel each other then molecule is non-polar.

In the given options,

SO2  is polar because the dipole moments on the O do not cancel.

PCl3  is polar because the P-Cl bonds do not cancel out.

CH2Cl2  polar because the C-Cl bonds do not cancel.

Hence, in brief, Polar molecules are molecules with net dipole due to the presence of partial positive and partial negative charge.

For example, water is a polar molecule that has partial positive and partial negative charge on it. CO2 is a non polar compound.

Therefore, all the given options SO2, CH2Cl2 and PCl3 are Polar molecules.