91Ó°ÊÓ

There are rules for naming alkene:

Cis configuration is when two groups are on the same face of the double bond and trans configuration is when the groups are on opposite faces.

Both isomers are stable and neither can be converted into the other without breaking and reforming chemical bonds.

Cis alkenes are less stable than their trans form as there is steric strain between the two bulky substituents on the same side of the double bond.

The condition for cis-trans isomerism in alkenes is that both of their carbons must be bonded to two different groups only then is cis-trans isomerism possible.

If one of their carbons bonded to two identical groups then cis-trans isomers can’t exist.

The structure of a given compound can exist in cis and trans forms as both carbons have two different groups attached.

Here, it can be seen that hydrogen is on the same side and the alkyl group are on the same side so it is a cis isomer.

Based on the above steps, the name of the compound is: $\mathrm{cis}−4,5−\mathrm{Dimethyl}−2−\mathrm{hexene}$