Q.134 Botany ⭐ 360° Option Elimination Active

NEET 2026 Botany Question 134 Solution

Topic: Biomolecules · Official NTA Booklet Code 50

Question

Arrange the following elements in descending order of their contribution to percentage weight of the human body. (a) Oxygen (b) Carbon (c) Hydrogen (d) Nitrogen Choose the correct answer from the options given below:

(1)(a), (b), (c), (d)
(2)(c), (a), (b), (d)
(3)(b), (c), (d), (a)
(4)(b), (a), (c), (d)

✓

Verified Against NTA Final Answer Key

Option (1) : (a), (b), (c), (d)

📚 Biomolecules Medium

📋 Given Parameters & Problem Setup

Elements to Order (a) Oxygen, (b) Carbon, (c) Hydrogen, (d) Nitrogen

Sorting Criterion Descending order of contribution to % weight of the human body

⚡

The 30-Second Exam Hall Shortcut: ⚡ O-C-H-N Abundance Order

⏱️ Save ~40 seconds

Human body weight: Oxygen (65%) > Carbon (18.5%) > Hydrogen (~10%) > Nitrogen (3.3%)!

1 Recall elemental mass composition in human physiology / living systems:

2 Oxygen (O) = ~65.0% (due to high water content H₂O).

3 Carbon (C) = ~18.5% (backbone of all organic biomolecules).

4 Hydrogen (H) = ~9.5 - 10.0% (constituent of water and organic molecules).

5 Nitrogen (N) = ~3.2 - 3.3% (amino acids, nucleic acids).

6 Descending order: Oxygen (a) > Carbon (b) > Hydrogen (c) > Nitrogen (d).

7 Direct sequence: (a), (b), (c), (d).

8 Select Option (1) in under 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: Standard biological elemental composition: O (65%) > C (18.5%) > H (~10%) > N (3.3%). Matches NTA final answer key Option A / (1).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Elemental Composition of the Human Body by Weight

Living tissues are predominantly composed of water (70–90% of total cell mass) along with proteins, lipids, nucleic acids, and carbohydrates. Because water ( $H_2O$ ) has a molecular weight of 18 with 16 parts Oxygen and 2 parts Hydrogen, Oxygen contributes the overwhelming majority of body mass.

\begin{aligned} \text{Oxygen (O)} &: \mathbf{65.0\%} \\ \text{Carbon (C)} &: \mathbf{18.5\%} \\ \text{Hydrogen (H)} &: \mathbf{9.5 - 10.0\%} \\ \text{Nitrogen (N)} &: \mathbf{3.2 - 3.3\%} \end{aligned}

• Calcium (~1.5%) and Phosphorus (~1.0%) follow Nitrogen.

Step 2

Determine Descending Order

Arranging in descending order (highest percentage to lowest percentage):

\text{Oxygen (a)} > \text{Carbon (b)} > \text{Hydrogen (c)} > \text{Nitrogen (d)}

• (a) Oxygen: 65%
• (b) Carbon: 18.5%
• (c) Hydrogen: ~9.5 - 10%
• (d) Nitrogen: ~3.3%

Step 3

Match with Given Options

Sequence: (a), (b), (c), (d). This corresponds directly to Option (1).

\text{Descending Sequence} = (\text{a}), (\text{b}), (\text{c}), (\text{d}) \implies \text{Option (1)}

• Matches official NTA final answer key Option A / (1).

⭐

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 A

✓ 100% Correct

Verdict & Scientific Reason:

100% accurate. O (65%) > C (18.5%) > H (~10%) > N (3.3%) in human body composition by weight.

💡

Why this is airtight: None; precise command of biochemistry.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Places Hydrogen as highest, confusing atom count with percentage weight.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing atomic percentage (number of atoms) with mass/weight percentage.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Places Oxygen at the very end despite it being 65% of body mass.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming organic chemistry implies Carbon is heaviest in the body.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Places Carbon (18.5%) ahead of Oxygen (65%).

⚠️

Student Fallacy (Why candidates pick this trap): Forgetting that water mass makes Oxygen far heavier than Carbon in living systems.

⚠️

NTA Trap Alert: Atomic Number vs Weight Percentage Confusion

By number of atoms, Hydrogen is most abundant ( $H_2O$ has 2 hydrogens per oxygen). But BY WEIGHT (percentage mass), Oxygen dwarfs all other elements because atomic mass of O is 16 versus 1 for H.

🛡️ How to avoid the -1 mark: Remember: Water is heavy because of OXYGEN! Oxygen is #1 by weight.

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Biomolecules Standard Benchmark

Core Scientific Principle Tested:

"In the human body by weight, the primary elements in descending order are Oxygen (65%) > Carbon (18.5%) > Hydrogen (~10%) > Nitrogen (3.3%)."

Syllabus Focus: How to Analyse Chemical Composition? - Table 9.1

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

O-C-H-N: Oxygen Crowns Human Nature in weight!

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NEET 2026 Botany Question 134 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ O-C-H-N Abundance Order

Step-by-Step Rigorous Workflow & Mathematical Proof

Elemental Composition of the Human Body by Weight

Determine Descending Order

Match with Given Options

360° Option Elimination Engine Key Feature

NTA Trap Alert: Atomic Number vs Weight Percentage Confusion

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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