Question

Which of the following effects is a permanent effect?

• A. Electromeric effect
• B. Inductive effect
• C. Both
• D. None

Hint:

A simple memory trick:
• Inductive Effect \(\rightarrow\) Permanent
• Electromeric Effect \(\rightarrow\) Temporary (appears only when reagent attacks)

Answer 1

The Correct Option is B

Concept: Organic molecules exhibit various electronic effects due to the movement or displacement of electrons. These effects influence stability, reactivity, acidity, basicity, and reaction mechanisms. Among the most important electronic effects are:
• Inductive Effect
• Electromeric Effect
• Resonance Effect
• Hyperconjugation Some of these effects are permanent while others occur only temporarily during a reaction.

Step 1: Understand the Inductive Effect
The inductive effect is the permanent displacement of sigma (\(\sigma\)) electrons along a carbon chain due to differences in electronegativity. This effect remains present in the molecule even when no attacking reagent is nearby. Examples: \[ \text{-NO}_2,\ \text{-CN},\ \text{-COOH} \] show strong electron-withdrawing (\(-I\)) effect. \[ \text{-CH}_3,\ \text{-C}_2\text{H}_5 \] show electron-releasing (\(+I\)) effect. Since this effect exists permanently within the molecule, \[ \boxed{\text{Inductive Effect is a permanent effect}} \]

Step 2: Understand the Electromeric Effect
The electromeric effect involves complete transfer of \(\pi\)-electrons in the presence of an attacking reagent. It appears only during the course of a reaction. Once the reagent is removed, the effect disappears. Therefore, \[ \boxed{\text{Electromeric Effect is a temporary effect}} \] and not a permanent one.

Step 3: Evaluate the options
Option (A): Electromeric effect Temporary effect. Incorrect. Option (B): Inductive effect Permanent effect. Correct. Option (C): Both Incorrect because electromeric effect is not permanent. Option (D): None Incorrect because inductive effect is definitely permanent. Final Conclusion: Among the given electronic effects, only the inductive effect is permanent in nature. Hence, \[ \boxed{\text{Correct Answer}=(B)\ \text{Inductive Effect}} \]