Which of the following is 'z' isomer?

Conclusion:

→ In order to exhibit geometrical isomerism, double bonded carbon should possess two different groups.

→ The C₁ carbon two groups and C₂ carbons two groups may (or) may not be same.

→ Either C₁ carbon two groups (or) C₂ carbon two groups are identical then geometrical isomerism is not possibel.

→ If all the four groups are different [a,b,c,d], then they donot exhibit CIS, trans isomerism but they exhibit geometrical isomerism i.e., E, Z-isomerism

→ If identical priority groups are on same side of the double bond then it is said to be Z-isomer.

→ If identical priority groups are on opposite side of the double bond,then it is said to be E-isomer.