Question

CC14 is non-polar but H2O is polar.why?

Answer 1

The four bonds of carbon tetrachloride (CCl4) are polar, but the molecule is nonpolar because the bond polarity is canceled by the symmetric tetrahedral shape. When other atoms substitute for some of the Cl atoms, the symmetry is broken and the molecule becomes polar.

Water (H2O) is a polar molecule because the electrons of the hydrogen atoms get "pulled" towards the electrons of the oxygen atom. This makes a region of positive charge on the hydrogen atoms and the negative charge on the other end of the molecule, which is the oxygen atom. This also allows for hydrogen bonding.

(Hope it helps!!)