Explain: (a) Octet rule for formation of sodium chloride (b) Duplet rule for formation of hydrogen.

Octet Rule for Formation of Sodium Chloride: Elements combine with each other to achieve a stable electronic configuration, often resembling the nearest inert gas. For instance, a sodium atom has one electron in its outermost shell. To achieve stability, it donates this single electron to a chlorine atom, which has seven electrons in its valence shell. By accepting one electron, the chlorine atom also achieves a stable configuration of eight electrons, similar to the electronic configuration of a noble gas. This tendency of atoms to have eight electrons in their valence shell is known as the octet rule. Consequently, the combination of these elements results in the formation of sodium chloride (NaCl).

Duplet Rule for Formation of Hydrogen: A hydrogen atom has a single electron in its valence shell. To achieve a stable configuration, similar to that of helium (which has two electrons, known as the duplet state), a hydrogen atom shares its electron with another hydrogen atom. When two hydrogen atoms each contribute one electron, both atoms essentially share two electrons, achieving a stable configuration. This sharing leads to the formation of a hydrogen molecule (H₂), adhering to the duplet rule.