Question

In which of the following cases is a polar covalent bond formed?

when the electrons of a bond are shared equally by the two atoms

when the electrons of a bond are shared unequally by the two atoms

when an electron is transferred from one atom to another

when a metallic element forms a bond with a non-metallic element

Answer 1

Covalnet bond is formed by sharing of electrons equally by both the atoms. Example: CH4

The electronic configuration of C is 1S²2s²2p². There are four electrons in the outermost orbit of C. It needs four electrons for satisfying the octet rule of 8 eletrons in the outermost orbit. The electronic configuration of H is 1s1. when 4 H atoms comnine with C. four electrons from H are available for Carbon and they are shared equally between Carbon and Hydrogen.

In case of ionic bond, one atom completely looses electrons to other atoms. EX; HCl. In case of chlorine, there are 7 electrons in the outermost orbit of Chlorine and takes 1 electrons from hydrogen. This is normally formed between a metallic element and non-metallic elemnet. Ex: NaCl.

in case of polar covalent compound, one atom will have more electronegativity than the other atoms and the sharing becomes unequal due to this. B is the correct answer.