Covalent bonds are formed by the sharing of electron pairs between two atoms. Atoms share electrons to achieve a more stable electron configuration, typically filling their valence shells.

The molecular formula of methane is CH₄, indicating that it contains one carbon atom bonded to four hydrogen atoms.

Carbon achieves noble gas configuration in methane by sharing its four valence electrons with four hydrogen atoms, forming four single covalent bonds. This allows carbon to attain a stable octet configuration, similar to noble gases.

Carbon in methane has a valency of 4, as it shares its four valence electrons with four hydrogen atoms to achieve stability.

In a molecule of ammonia, single covalent bonds are present between the nitrogen atom and each of the three hydrogen atoms.