Q.100 Chemistry · Section B ⭐ 360° Option Elimination Active

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NEET 2024 Chemistry Question 100 Solution

Topic: Electrochemistry · Official NTA Booklet Code T1

Question

calories remaining percentage of C. Then, the empirical formula of X is :

(1)0 calorie
(2)-413.14 calories (Given atomic masses ofA=64; B =40; C =32 u) (1） AB2C2
(3)ABC4 92 For the given reaction:
(4)A2BC2

✓

Verified Against NTA Final Answer Key

Option (4) : 0.315 g

📚 Electrochemistry Easy

📋 Given Parameters & Problem Setup

Current (I) 9.6487 A

Time of electrolysis (t) 100 seconds

Molar mass of copper (Cu) 63 g mol^-1

Faraday constant (1F) 96487 C

⚡

The 30-Second Exam Hall Shortcut: ⚡ Exact Decimal Cancellation Hack

⏱️ Save ~40 seconds

Q = I · t = 9.6487 A × 100 s = 964.87 C! Faradays = 964.87 / 96487 = 0.01 F! Cu²⁺ + 2e⁻ -> Cu: 1 F deposits 63/2 = 31.5 g -> 0.01 F deposits 0.315 g!

1 Compute total charge passed: Q = I × t = 9.6487 A × 100 s = 964.87 C.

2 Convert charge to Faradays: n_F = Q / F = 964.87 / 96487 = 0.01 F.

3 Reduction half-reaction: Cu²⁺ + 2e⁻ -> Cu.

4 2 Faradays deposit 1 mole of Cu (63 g).

5 1 Faraday deposits equivalent weight = 63 / 2 = 31.5 g.

6 0.01 Faraday deposits: 0.01 × 31.5 g = 0.315 g.

7 Option (4) in 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Chemistry · Electrochemistry (Faraday’s first law of electrolysis: m = Z · I · t = (M / nF) · I · t).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Cathodic Reduction Half-Reaction

In the electrolysis of copper sulphate (CuSO4) solution, cupric ions (Cu²⁺) are reduced at the cathode by accepting two electrons per atom:

\text{Cu}^{2+}(\text{aq}) + 2e^\ominus \longrightarrow \text{Cu}(\text{s}) \implies z = 2\; e^\ominus / \text{atom}

Step 2

Calculation of Total Electrical Charge Q

Using Q = I × t where current I = 9.6487 A and time t = 100 s:

Q = I \cdot t = (9.6487\;\text{A}) \times (100\;\text{s}) = 964.87\;\text{C}

Step 3

Faraday’s First Law Formulation

According to Faraday’s First Law of Electrolysis, the mass m of substance deposited is proportional to charge Q:

m = \frac{\text{Molar Mass}}{z \cdot F} \times Q = \frac{M \cdot I \cdot t}{z \cdot F}

Step 4

Substitution and Decimal Evaluation

Substituting M = 63 g/mol, z = 2, F = 96487 C, and Q = 964.87 C:

m = \frac{63\;\text{g/mol}}{2 \times 96487\;\text{C}} \times 964.87\;\text{C} = \frac{63}{2} \times \left(\frac{964.87}{96487}\right) = 31.5 \times 0.01 = 0.315\;\text{g}

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 (1)

✗ Incorrect

Verdict & Scientific Reason:

Represents mass deposited by 1 whole Faraday (100 times too large).

⚠️

Student Fallacy (Why candidates pick this trap): Forgetting the 0.01 factor.

2 (2)

✗ Incorrect

Verdict & Scientific Reason:

Off by a factor of 10.

⚠️

Student Fallacy (Why candidates pick this trap): Dividing by 20 instead of 2.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

Off by a factor of 10 (assumes 0.1 Faraday).

⚠️

Student Fallacy (Why candidates pick this trap): Miscounting decimal places.

4 (4)

✓ 100% Correct

Verdict & Scientific Reason:

Exact mathematical calculation: (63 / 2) × 0.01 = 0.315 g.

💡

Why this is airtight: None.

⚠️

NTA Trap Alert: Decimal Position Confusion (31.5 vs 3.15 vs 0.315)

964.87 / 96487 is exactly 1/100 = 0.01. Multiplying 31.5 by 0.01 shifts the decimal point two places to the left: 0.315 g.

🛡️ How to avoid the -1 mark: 31.5 × 10⁻² = 0.315 g. Double check decimal shifts.

📖

Core NEET Syllabus Standard

Chemistry Core Physical Chemistry · Electrochemistry Standard Benchmark

Core Scientific Principle Tested:

"Mass of substance deposited in electrolysis is m = (M / nF) · I · t."

Syllabus Focus: Quantitative Aspects of Electrolysis: Faraday’s Laws

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Hundred seconds at 9.6487 makes point-zero-one Faraday: Thirty-one point five times that gives zero-point-three-one-five right away!

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NEET 2024 Chemistry Question 100 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Exact Decimal Cancellation Hack

Step-by-Step Rigorous Workflow & Mathematical Proof

Cathodic Reduction Half-Reaction

Calculation of Total Electrical Charge Q

Faraday’s First Law Formulation

Substitution and Decimal Evaluation

360° Option Elimination Engine Key Feature

NTA Trap Alert: Decimal Position Confusion (31.5 vs 3.15 vs 0.315)

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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