Which of the following statements about geometrical isomerism is/are correct? (a) It is also called cis-trans isomerism. (b) It is exhibited by alkenes only. (c) Alkynes can also show geometrical isomerism. (d) In cis-isomer identical groups are on same side.
Hint: Geometrical Isomerism what is this property, which hydrocarbons shows these properties and which not, alternate names, Geometrical isomerism is sub-type of which isomerism and detailed knowledge about the Geometrical Isomerism.
Complete answer: We start with the definition of geometrical isomerism: Geometrical isomerism: The isomerism in which the chemical compounds are having the same molecular formula, same functional groups but the spatial arrangement of some compounds are different. Geometrical Isomerism is the sub-type of StereoIsomerism. Conditions of Geometrical Isomerism: 1) The hydrocarbon must have at-least one double bonded carbon atoms to satisfy the condition, i.e, the hydrocarbon must be alkene (Alkene: The carbon with at-least one double bonded carbon is called Alkene.) 2) In these types of isomerism, if the two identical atoms or groups are on the same side of the carbon’s double bond known as cis isomer and , if the two identical atoms or groups are on the opposite side of the carbon’s double bond is called trans isomer. That is why Geometrical Isomers are also called cis-trans Isomers.
Hence, this question has multi-correct options, the correct options are (a), (b) and (d).
Additional information: So, let’s start with the definition of Isomerism. Isomerism: Isomerism is the property of hydrocarbons in which they have the same chemical formula but their structures are different. There are two types of Isomerism: (a) Structural Isomerism (b) Stereo Isomerism Structural Isomerism are of four types: (a) Chain Isomerism (b) Position Isomerism (c) Functional group Isomerism (d) Metamerism Stereo Isomerism are of two types: (a) Geometrical Isomerism (b) Optical Isomerism
Note: If the two atoms or groups are not same, although they will show the Geometrical isomerism. Then the Geometrical Isomerism will be named as E and Z transform depending upon the priority of atoms or groups.