Question

Which of the following will show GI?
A.

B.

C.

D. All of these

Answer 1

Hint:. For geometrical isomerism to occur, the compound must have at least one double bond of carbon and the groups or atoms that are attached to the double bonded carbon must be different.

Complete step by step answer:
In order to answer our question, let us get to know some facts about isomerism. Two or more compounds having the same molecular formula but different physical and chemical properties are called isomers and this phenomenon is called isomerism. Geometrical isomerism is a type of stereoisomerism. The compounds having the same molecular as well as same structural formulae but differing in the relative arrangement of the atoms or groups in space are called stereoisomers and the phenomenon, stereomerism respectively. In alkenes,the geometrical isomerism is because of restricted or hindered rotation across double bonds of carbon. As a result, the organic compounds of the type ${{C}_{2}}{{A}_{2}}{{B}_{2}}$ with structural formula BAC = CAB represent two spatial arrangements or isomers, named geometrical isomers. If the groups are present on the same side of the double bond, then it is called a cis isomer. Whereas, if it is present on opposite sides, then we call it the trans isomer.

Condition for geometrical isomerism:
A. It must have at least one carbon-carbon double bond in it.
B. The atoms or groups attached to the double bonded carbon must be different.
As we can see that only one option i.e compound of option A satisfies the above conditions. It is the only compound that is an alkene, having double bonds and different groups. So, compound A will show geometrical isomerism and hence our answer is option A.
So, the correct answer is “Option A”.

Note: Following points are to be noted regarding cis and trans isomers:
a. Dipole moment of cis isomer is normally higher than that of trans isomer.
b. The boiling point and melting point of cis isomer is higher than trans isomer.
c. Trans isomers are more stable than cis isomers, due to less repulsion.