Question

Which formula represents an alkene?

Answer 1

Alkenes are organic compounds which contains double bonds between two carbon atoms. The formula C2H4 can be classified as an alkene since it most likely contains a double bond between the carbon-carbon atoms. An alkene has the general formula of CnH2n.

Answer 2

The question is incomplete, here is a complete question.

Which formula represents an alkene?

(a) $CH_4$

(b) $C_2H_4$

(c) $C_2H_6$

(d) $C_2H_5OH$

Answer : The correct option is, (b) $C_2H_4$

Explanation :

Hydrocarbons are the type of organic compound that contains only hydrogen and the carbon atoms.

Saturated hydrocarbon : These are those hydrocarbons in which all carbon atoms and hydrogen atoms are bonded together with single bonds. The general formula of saturated hydrocarbon (alkane) is, $C_nH_{2n+2}$

For example : Methane, Ethane, etc.

Unsaturated hydrocarbon : These are those hydrocarbons in which carbon-carbon atom bonded together with double or triple covalent bonds.

The general formula of unsaturated double bond hydrocarbon (alkene) is, $C_nH_{2n}$

The general formula of unsaturated triple bond hydrocarbon (alkyne) is, $C_nH_{2n-2}$

For example : Ethene, Butyne, etc.

As per question,

(a) $CH_4$ : It is a saturated hydrocarbon and the name of this hydrocarbon is methane.

(b) $C_2H_4$ : It is an unsaturated hydrocarbon and the name of this hydrocarbon is ethene.

(c) $C_2H_6$ : It is a saturated hydrocarbon and the name of this hydrocarbon is ethane.

(d) $C_2H_5OH$ : It is a saturated hydrocarbon and the name of this hydrocarbon is ethanol.

Hence, the formula represents an alkene is, $C_2H_4$