Question

what is tetravelency....​

Answer 1

$Carbon \: has \: a \: valency \: of four, \: so \: it \: is \: capable \: of bonding \: with \: four \: other \: atoms \: of \: carbon \: or \: atoms \: of \: some \: other \: monovalent \: element. \: This \: is \: known \: as  \: tetravalency \:  of \: carbon \: .$

Carbon has a valency of four, so it is capable of bonding with four other atoms of carbon or atoms of some other monovalent element. This is known as tetravalency of carbon.