Question

\(\mathrm{P}\) and \(\mathrm{Q}\) can be related as (A) Positional isomers (B) Identical (C) Optical isomer (D) Geometrical isomer

Short answer

Without specific information about compounds P and Q, it is impossible to determine their relation accurately. They could potentially be positional isomers (A), identical compounds (B), optical isomers (C), or geometrical isomers (D) based on their structures and properties. More information is needed to select the correct option.

Step-by-step solution

Identify Compounds and their Isomers

Since we aren't given any specific compounds P and Q, we can only provide a generic answer. Depending on the compounds examined, they could potentially relate to one another as positional isomers, identical compounds, optical isomers, or geometrical isomers.

Match the Relation with the Given Options

Below, we've summarized the definitions for each option again, so you can match them with the relation you've determined in Step 1. (A) Positional Isomers: Isomers that differ in the position of a functional group or substituent on the parent chain. (B) Identical: Compounds that are exactly the same in structure and properties. (C) Optical Isomers: Isomers that are non-superimposable mirror images of each other. (D) Geometrical Isomers: Isomers that have the same molecular formula but different spatial arrangements of the atoms due to restricted rotation about a bond. Choose the option that best describes the relationship between compounds P and Q.

Key concepts

Positional Isomers

Isomers are fascinating variations of molecules that share the same molecular formula but differ structurally. Positional isomers are one such variety, where the difference lies in the location of a particular functional group or substituent on the parent carbon chain. For instance, if you have a structure with a hydroxyl group (-OH), its position can change, leading to different positional isomers.

Let's take an example of butanol to understand better. In butanol, moving the -OH group around can yield 1-butanol, 2-butanol, and so forth. Each of these isomers possesses distinct properties like boiling point, solubility, and reactivity.

• This difference in position affects how the molecule interacts with other substances.
• Different positional isomers can significantly change the physical and chemical properties of the compound.

Thus, these isomers play an essential role in the field of chemistry, offering a range of options for chemical synthesis and applications.

Optical Isomers

Optical isomers, also referred to as enantiomers, are a unique type of isomerism marked by their non-superimposable mirror image structures. Imagine two hands: although they look similar, you cannot perfectly align the left and right hands. This analogy helps describe optical isomers.

These isomers occur due to the presence of a chiral center, usually a carbon atom bonded to four different substituents. This setup creates two possible arrangements, each being a non-superimposable mirror image of the other.

• Optical isomers are significant in fields like pharmacology since one enantiomer can provide therapeutic effects, while its mirror could be inactive or even harmful.
• The terms 'dextrorotatory' and 'levorotatory' (often denoted by 'D-' and 'L-') describe the direction these isomers rotate plane-polarized light.

The study of optical isomers is crucial in understanding molecular interactions, especially in biological systems, making it a key area in stereochemistry.

Geometrical Isomers

Geometrical isomers, also known as cis-trans isomers, arise due to restricted rotation around a double bond or other rigid structures like rings. This type of isomerism involves molecules that have the same molecular formula but differ in the spatial orientation of substituents.

A classic illustration involves 2-butene. Here, the substituents can be on the same side (cis-2-butene) or on opposite sides (trans-2-butene) of the double bond. This orientation impacts the molecule's physical and chemical properties.

• Geometrical isomers can vary in boiling point, melting point, and even reactivity.
• Cis isomers usually have higher polarities, leading to higher boiling points than their trans counterparts.

Understanding geometrical isomers provides insight into molecular shapes and their effects, which is particularly useful in industrial applications, including pharmaceuticals and materials science.