Standard of Comparison Explained | CBSE Class 11 Physics | NEET Notes
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| Standard of Comparison in Physics with real-life examples for NEET and CBSE students. |
- Dr. Sanjaykumar Pawar
Q. 1.4 Explain this statement clearly:
“To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for comparison.”
Answer (CBSE Topper Style)
A dimensional physical quantity has both magnitude and unit. Whether it is called large or small depends on what it is being compared with.
Therefore, simply saying that a quantity is "large" or "small" has no meaning unless a standard or reference quantity is mentioned.
Example:
- A distance of 10 m is large compared to the size of a classroom but very small compared to the distance between two cities.
Hence, every statement describing a dimensional quantity as large or small should include a suitable standard of comparison.
Reframing the given statements
(a) Atoms are very small objects.
Reframed Statement:
Atoms are very small compared to ordinary objects, such as a grain of sand or a pinhead.
(b) A jet plane moves with great speed.
Reframed Statement:
A jet plane moves with great speed compared to road vehicles, but its speed is much smaller than the speed of light.
(c) The mass of Jupiter is very large.
Reframed Statement:
The mass of Jupiter is very large compared to the mass of the Earth (or any other planet like Mars).
(d) The air inside this room contains a large number of molecules.
Reframed Statement:
The air inside this room contains a very large number of molecules compared to the number of people or other visible objects present in the room.
(e) A proton is much more massive than an electron.
Answer:
This statement is already meaningful because it clearly specifies the standard of comparison (electron).
(f) The speed of sound is much smaller than the speed of light.
Answer:
This statement is already meaningful because it compares the speed of sound with the speed of light, providing a clear standard of comparison.
Final Answer (Exam Points)
- A quantity can be called large or small only with respect to a specified standard or reference.
- Without comparison, such statements are meaningless.
Corrected Statements:
(a) Atoms are very small compared to ordinary objects.
(b) A jet plane moves with great speed compared to road vehicles.
(c) The mass of Jupiter is very large compared to the mass of the Earth.
(d) The air inside this room contains a very large number of molecules compared to the number of people in the room.
(e) No change required, as the comparison is with an electron.
(f) No change required, as the comparison is with the speed of light.
NEET Master Learning Structure (NMLS)
हर टॉपिक के लिए एक यूनिवर्सल फॉर्मेट
1. Topic Name
Chapter: Units and Measurements
Topic: Standard of Comparison (Large & Small Quantities)
2. One-Line Definition (Exam Definition)
Rule:
किसी भी भौतिक राशि (Physical Quantity) को "बड़ा" या "छोटा" तभी कहा जा सकता है जब उसके साथ तुलना (Comparison) का मानक (Standard) दिया गया हो।
3. Why? (Concept Building)
याद रखने वाला नियम
👉 बड़ा या छोटा = हमेशा तुलना
यदि तुलना नहीं है तो कथन अधूरा है।
4. Visual Flow Chart
Physical Quantity
│
▼
Large / Small ?
│
▼
Compared With?
/ \
Yes No
│ │
Meaningful Meaningless
5. Memory Trick (Mnemonic)
Mnemonic
"LSC"
L → Large
S → Small
C → Comparison
Large or Small ⇒ Comparison Must
दूसरा आसान Mnemonic
"No Comparison = No Conclusion"
(NC = NC)
6. Quick Table
| Statement | Comparison Given? | Correct / Incorrect |
|---|---|---|
| Atom is small | ❌ No | Incorrect |
| Atom is smaller than a grain of sand | ✅ Yes | Correct |
| Jet is fast | ❌ No | Incorrect |
| Jet is faster than a car | ✅ Yes | Correct |
| Proton is heavier than electron | ✅ Yes | Correct |
| Speed of sound is less than speed of light | ✅ Yes | Correct |
7. Comparison Table
| Quantity | Compared With | Final Statement |
|---|---|---|
| Atom | Everyday objects | Very small |
| Jet Plane | Car | Very fast |
| Jupiter | Earth | Very massive |
| Air Molecules | Humans | Very large number |
| Proton | Electron | Much heavier |
| Sound | Light | Much slower |
8. Mind Map
Large / Small
│
┌───────────┼───────────┐
│ │ │
Heavy Fast Long
│ │ │
└───────────┼───────────┘
│
Need Comparison
│
Otherwise Wrong
9. Common Mistakes
❌ Atom is very small.
✔ Atom is very small compared to everyday objects.
❌ Car is very fast.
✔ Car is faster than a bicycle.
❌ Jupiter is very massive.
✔ Jupiter is much more massive than Earth.
10. Examiner's Favourite Questions
Type-1
Explain why comparison is necessary.
Type-2
Rewrite the statement correctly.
Type-3
Which statement is meaningful?
Type-4
Assertion-Reason
Type-5
Choose the incorrect statement.
11. NEET Trick
Whenever you read these words
Large
Small
Heavy
Light
Fast
Slow
High
Low
Long
Short
Immediately ask
"Compared to What?"
यदि उत्तर मिल गया
✅ Statement Correct
यदि उत्तर नहीं मिला
❌ Statement Incorrect
12. PYQ Thinking Method
Question पढ़ते ही
STEP-1
Physical Quantity पहचानो
↓
STEP-2
Large/Small लिखा है?
↓
STEP-3
Comparison दिया है?
↓
Yes → Correct Statement
No → Wrong Statement
13. 10-Second Revision
✔ Large = Relative
✔ Small = Relative
✔ Heavy = Relative
✔ Fast = Relative
✔ Comparison Must
✔ No Comparison = No Meaning
14. Golden Rule (100% Exam Point)
यदि किसी वाक्य में Large, Small, Heavy, Light, Fast, Slow, High या Low लिखा हो, तो तुरंत जाँचें कि तुलना (Comparison) दी गई है या नहीं।
यदि तुलना नहीं दी गई है, तो कथन वैज्ञानिक रूप से अधूरा (Meaningless) माना जाएगा।
15. One-Line Formula
Large/Small + Comparison = Meaningful Statement
Large/Small − Comparison = Meaningless Statement
NEET Practice Question Bank
Chapter: Units and Measurements
Topic: Standard of Comparison (Large & Small Quantities)
Section A: Direct MCQs (Single Correct Option)
Easy Level
Q1.
Which of the following statements is scientifically meaningful?
A. A mountain is very high.
B. An atom is very small.
C. A proton is more massive than an electron.
D. A river is very long.
✅ Answer: C
Explanation: Only option C provides a standard of comparison.
Q2.
Which statement is incomplete?
A. Earth is larger than the Moon.
B. Light travels faster than sound.
C. Jupiter is more massive than Earth.
D. A train is very fast.
✅ Answer: D
Moderate Level
Q3.
Which statement correctly follows the principle of comparison?
A. Molecules are tiny.
B. A jet plane is fast compared to a bicycle.
C. A room contains many molecules.
D. The Sun is hot.
✅ Answer: B
Q4.
Which statement is NOT meaningful?
A. A proton is heavier than an electron.
B. Sound travels slower than light.
C. Mercury is smaller than Earth.
D. Iron is very heavy.
✅ Answer: D
Hard Level
Q5.
Which option correctly identifies all meaningful statements?
-
Atom is very small.
-
Proton is heavier than electron.
-
Speed of light is greater than speed of sound.
-
Jupiter is very massive.
Options
A. 1 and 4
B. 2 and 3
C. 1,2,3
D. All
✅ Answer: B
Section B: Statement-Based Questions
Q6.
Statement I
Every physical quantity described as "large" or "small" requires a comparison.
Statement II
Without a standard of comparison, such statements are scientifically incomplete.
A. Both statements are true and II explains I.
B. Both true but II does not explain I.
C. I true II false.
D. I false II true.
✅ Answer: A
Q7.
Statement I
The statement "An atom is very small" is scientifically complete.
Statement II
A meaningful statement must include a standard of comparison.
A. TT
B. TF
C. FT
D. FF
✅ Answer: C
Section C: Assertion & Reason
Q8.
Assertion (A)
"The speed of sound is much smaller than the speed of light."
Reason (R)
The statement specifies a standard for comparison.
A. Both A and R are true, and R is the correct explanation.
B. Both true but R is not the explanation.
C. A true R false.
D. A false R true.
✅ Answer: A
Q9.
Assertion
"A jet plane moves with great speed."
Reason
The statement gives the comparison standard.
A. TT Correct Explanation
B. TT Wrong Explanation
C. TF
D. FT
✅ Answer: C
Section D: Match the Columns
Column I
A. Atom
B. Proton
C. Sound
D. Jupiter
Column II
-
Compared with Earth
-
Compared with Electron
-
Compared with Light
-
Compared with Everyday Objects
Correct Matching
A → 4
B → 2
C → 3
D → 1
Answer
A-4
B-2
C-3
D-1
Section E: Diagram-Based Question
Flow Chart
Statement
│
▼
Large / Small ?
│
┌──────┴──────┐
│ │
Comparison Given? No Comparison
│ │
▼ ▼
Meaningful Meaningless
Question
The statement
"Gold is heavy."
lies in which branch?
A. Meaningful
B. Meaningless
C. Dimensionless
D. Scalar
✅ Answer: B
Section F: Higher Order Thinking (HOTS)
Q10.
A student writes
"The Earth is very large."
The teacher marks it incorrect.
Which correction is most appropriate?
A. Earth is large compared to the Moon.
B. Earth is always large.
C. Earth is absolutely large.
D. Earth has a large radius.
✅ Answer: A
Q11.
Which one of the following is an example of a relative statement?
A. Length is measured in metre.
B. Speed of light is constant.
C. The Himalayas are higher than the Aravalli Hills.
D. Mass is a fundamental quantity.
✅ Answer: C
Section G: NEET PYQ-Type Mixed MCQs
Q12.
Identify the meaningful statements.
-
Air contains many molecules.
-
Jupiter is more massive than Earth.
-
Electron is lighter than proton.
-
Mountain is very high.
Options
A. 1,2
B. 2,3
C. 1,3
D. All
✅ Answer: B
Q13.
Which of the following words usually require a comparison to become scientifically meaningful?
-
Large
-
Small
-
Fast
-
Heavy
Options
A. Only 1
B. 1 and 2
C. 1,2,3
D. All
✅ Answer: D
Section H: Very Hard NEET Conceptual Question
Q14.
Which statement best explains why "The Sun is very large" is scientifically incomplete?
A. The Sun is not large.
B. Size has no unit.
C. No comparison standard has been specified.
D. The Sun's mass is unknown.
✅ Answer: C
Section I: NEET Trap Question
Q15.
Which one is correctly written?
A. Atom is tiny.
B. Jupiter is huge.
C. Proton is much heavier than electron.
D. Car is fast.
✅ Answer: C
Final Revision Trick
Whenever you read these words in a NEET question:
✔ Large
✔ Small
✔ Heavy
✔ Light
✔ Fast
✔ Slow
✔ High
✔ Low
Immediately ask:
👉 "Compared to What?"
If comparison is given → Correct
If comparison is missing → Incorrect or Incomplete
Internal Links
From this article link to
✔ Physical Quantities
✔ Fundamental and Derived Quantities
✔ SI Units
✔ International System of Units
✔ Dimensions
✔ Dimensional Formula
✔ Dimensional Analysis
✔ Significant Figures
✔ Errors in Measurement
✔ Scientific Notation
✔ Order of Magnitude
✔ Accuracy and Precision
✔ Vernier Calipers
✔ Screw Gauge
✔ NCERT Class 11 Physics Chapter 2 Notes
✔ NEET Physics MCQ Collection
✔ Physics Formula Sheet
✔ Previous Year Questions
