JUST ADDED: JEE Main 2026 (Jan 21) Question Paper with Analysis and Solution Attempt Now →
NEP 2020 Compliant

Competency-Based Assessment Made Simple.

A comprehensive platform for Teachers to create standard question papers and Students to practice Case-Based, Assertion-Reason, and Critical Thinking questions.

1,105+
Questions
5+
Subjects
100%
NEP Aligned

Generate Papers

Create professional PDF/Word papers with logo, instructions, and mixed question types in minutes.

Start Creating

Question Bank

Explore our repository by Class and Topic. Filter by "Knowledge" or "Competency" levels.

Browse Bank

Self-Regulated Test

For Students. Take timed MCQ tests to check your understanding. Get instant feedback.

Take Test
Pedagogy Shift

Why Competency-Based?

According to NEP 2020, rote learning is out. The focus has shifted to assessing a student's ability to apply concepts in real-life situations.

Case-Based Questions

Questions derived from real-world passages to test analytical skills.

Assertion-Reasoning

Testing the logic behind concepts, not just the definition.

Critical Thinking

Open-ended scenarios that require thinking beyond the textbook.

Marking Scheme
Randomly Fetched Question
Question
Correct order of acidic strength: (I) Phenol, (II) p-Cresol, (III) m-Nitrophenol, (IV) p-Nitrophenol
APPLY COMPETENCY 4 Marks
Concept Application
50%
Calculation / Logic
50%
Target Level
MEDIUM
Unique Feature

More Than Just an Answer Key

We provide complete AI-Powered Explanations for every question.

APPLY COMPETENCY MEDIUM

Q: Correct order of acidic strength: (I) Phenol, (II) p-Cresol, (III) m-Nitrophenol, (IV) p-Nitrophenol

Question Analysis & Solution

Step-by-Step Solution

1. Understanding Acidity of Phenols:

Phenols are acidic due to the ability of the phenoxide ion (formed after deprotonation) to be stabilized by resonance. Substituents on the benzene ring can either increase or decrease the acidity of the phenol.

2. Effect of Substituents:

  • Electron-Withdrawing Groups (EWG): EWGs (like -NO2) increase acidity by stabilizing the phenoxide ion through resonance and inductive effects. The more effective the EWG and the closer it is to the -OH group, the greater the increase in acidity.
  • Electron-Donating Groups (EDG): EDGs (like -CH3 in cresol) decrease acidity by destabilizing the phenoxide ion.

3. Analyzing the Given Compounds:

  • (I) Phenol: Base reference.
  • (II) p-Cresol: The -CH3 group is an EDG, so it will decrease the acidity compared to phenol.
  • (III) m-Nitrophenol: The -NO2 group is an EWG.
  • (IV) p-Nitrophenol: The -NO2 group is an EWG.

4. Comparing the Nitro-phenols:

Both m-Nitrophenol and p-Nitrophenol have a nitro group (-NO2), which is an EWG. The para isomer (p-Nitrophenol) is generally more effective at stabilizing the negative charge on the phenoxide ion due to resonance effects compared to the meta isomer (m-Nitrophenol). Therefore, p-Nitrophenol is more acidic than m-Nitrophenol.

5. Ordering the Acidic Strength:

Based on the above analysis, the order of acidic strength is: p-Nitrophenol > m-Nitrophenol > Phenol > p-Cresol, which translates to IV > III > I > II.

6. Checking the Options:

The closest option to our derived order is (A) III > I > II and (B) IV > I > II. However, we know IV > III, so we need to consider the options more carefully.

Option (C) IV > I > III > II is incorrect because it places Phenol (I) between p-Nitrophenol (IV) and m-Nitrophenol (III), which is not accurate as both nitrophenols are more acidic than phenol.

Considering the options again, we need to determine the relative acidity of Phenol (I) compared to m-Nitrophenol (III). Since -NO2 is a strong EWG, even in the meta position, m-Nitrophenol (III) will be more acidic than Phenol (I). Therefore, the correct order should be IV > III > I > II.

However, none of the options perfectly match this order. The closest is option (A) III > I > II and (B) IV > I > II. Since IV is more acidic than III, we need to re-evaluate.

The correct order is IV > III > I > II. However, the options provided do not include 'I'. The question is flawed. However, if we must choose from the given options, we need to consider the relative differences. p-Nitrophenol is significantly more acidic than m-Nitrophenol. Both are significantly more acidic than p-Cresol. Therefore, the best approximation from the given options is IV > III > II.

Correct Answer: IV > III > II

|
AI Suggestion: Option A
View Full Question Details →