Carbon has a covalency of 2 in CO and 4 in CO2 and CH4. Its valency in C2H2 is:

Explanation:
The valency of an element represents the number of bonds it can form with other elements. Carbon is a unique element in that it can form different numbers of bonds depending on the molecule it is a part of.

1. Carbon monoxide (CO):
In carbon monoxide, carbon forms a double bond with oxygen. Each bond involves the sharing of two electrons, resulting in a total of four shared electrons. Since each electron is shared between two atoms, carbon has a covalency of 2 in CO.

2. Carbon dioxide (CO2) and methane (CH4):
In carbon dioxide, carbon forms two double bonds with oxygen, while in methane, carbon forms four single bonds with hydrogen. Each bond still involves the sharing of two electrons, resulting in a total of eight shared electrons. Therefore, carbon has a covalency of 4 in both CO2 and CH4.

3. Acetylene (C2H2):
Acetylene is a hydrocarbon molecule with the formula C2H2. In this molecule, two carbon atoms are bonded together by a triple bond. Each bond involves the sharing of two electrons, resulting in a total of six shared electrons between the carbon atoms. Additionally, each carbon atom forms a single bond with a hydrogen atom, contributing another two shared electrons. Therefore, in C2H2, carbon has a covalency of 2 for the triple bond and 1 for the single bond, giving it a total valency of 3.

To summarize:
- Carbon has a covalency of 2 in CO, 4 in CO2, and CH4.
- In C2H2 (acetylene), carbon has a covalency of 2 for the triple bond and 1 for the single bond, resulting in a total valency of 3.

By following these rules, carbon can form different numbers of bonds and exhibit various valencies, allowing it to participate in the formation of a wide range of organic and inorganic compounds.

Acc to me its valency will be...2..because 1 carbon is making 2 bonds..1 with another C and 1 with H