Question

non polar molecules.......................

Answer 1

the molecules having their net dipole moment equals to zero are known as non polar molecules
For nonpolar bonds the electronegativity of the atoms will be equal. In a polar bond you will have an unequal sharing of electron pairs which causes a molecular dipole. Bonds will cancel or not depending on the shape of the molecule.

Answer 2

molecules which have ions equally distributed by both atoms shared by covalent bond. mainly molecules like cl2,i2 are good example of non polar molecule because atoms in it have same electonegativity ,so they share one electron because as in case of cl it needs one electron which will be shared by another cl atom which also requires 1 electron to become stable