NEET Unit Conversion Practice Questions with Answers | MCQ + Assertion Reason + PYQ

 - Dr.Sanjaykumar Pawar  

CBSE & NEET Physics Unit Conversion Notes, Tricks, MCQs & Shortcuts 

NEET Physics Unit Conversion Chart with formulas, shortcuts, and memory tricks for fast exam revision.

🔗 Internal Links 

/neet-physics-dimensions-analysis

/cbse-class-11-physics-units-and-measurement

/physics-mnemonics-tricks

/neet-mcq-practice-physics

/scientific-notation-shortcuts

/assertion-reason-questions-physics

/pyq-physics-class-11

Unit Conversion in Physics (CBSE Class 11)

1.2 Fill in the blanks by suitable conversion of units

(a) 1 kg m² s⁻² = ______ g cm² s⁻²

Step 1: 1 kg = 10³ g
Step 2: 1 m² = (10² cm)² = 10⁴ cm²
Step 3: Multiply
= 10³ × 10⁴ g cm² s⁻²
= 10⁷ g cm² s⁻²

(b) 1 m = ______ ly

1 light year = 9.46 × 10¹⁵ m
1 m = 1 / (9.46 × 10¹⁵) ly
= 1.06 × 10⁻¹⁶ ly

(c) 3.0 m s⁻² = ______ km h⁻²

Step 1: 1 m = 10⁻³ km → 3.0 m s⁻² = 3.0 × 10⁻³ km s⁻²
Step 2: 1 s⁻² = (3600)² h⁻² = 1.296 × 10⁷ h⁻²
Step 3: Multiply
= 3.0 × 10⁻³ × 1.296 × 10⁷
= 3.89 × 10⁴ km h⁻²

(d) G = 6.67 × 10⁻¹¹ N m² kg⁻² = ______ cm³ s⁻² g⁻¹

1 N = 1 kg m s⁻²
So, N m² kg⁻² = m³ s⁻² kg⁻¹

Convert units:
1 m³ = 10⁶ cm³
1 kg⁻¹ = 10⁻³ g⁻¹

Multiply factors:
= 10⁶ × 10⁻³ = 10³
= 6.67 × 10⁻¹¹ × 10³
= 6.67 × 10⁻⁸ cm³ s⁻² g⁻¹

Short Notes: Conversion of Units

1. Concept

Unit conversion is the process of expressing a physical quantity in different units without changing its value.

2. Basic Conversions

- 1 kg = 10³ g
- 1 m = 10² cm
- 1 km = 10³ m
- 1 h = 3600 s
- 1 ly = 9.46 × 10¹⁵ m

3. Derived Units

- Force: 1 N = 1 kg m s⁻²
- Energy: 1 J = 1 kg m² s⁻²
- Gravitational constant: G = N m² kg⁻² = m³ s⁻² kg⁻¹

4. Method

1. Write given quantity
2. Replace units with conversions
3. Apply powers correctly
4. Multiply and simplify

5. Important Tips

- Always use powers of 10
- Treat units like algebra
- Check final unit carefully

📘 Unit Conversion Master Structure (NEET + CBSE)

📊 1. Basic Conversion Table

Quantity	SI Unit	Conversion
Mass	kg	1 kg = 10³ g
Length	m	1 m = 10² cm
Length	km	1 km = 10³ m
Time	hour	1 h = 3600 s
Force	Newton	1 N = 1 kg m s⁻²
Energy	Joule	1 J = 1 kg m² s⁻²
Gravitational Constant	G	N m² kg⁻²

🌟 2. Power Conversion Rules

Base Unit	Conversion Power
m → cm	10²
m² → cm²	10⁴
m³ → cm³	10⁶
kg → g	10³
s → h	3600
s⁻² → h⁻²	(3600)²

🧠 3. Mnemonic Trick

Mnemonic: “M K G H L J N G”

Meaning:
M → Meter
K → Kilometer
G → Gram
H → Hour
L → Light Year
J → Joule
N → Newton
G → Gravitational Constant

Memory Line:
“My King Gives High Level Job New Goals”

⚡ 4. Fast Solving Method

STEP 1 → Convert each unit separately
STEP 2 → Apply power rules carefully
STEP 3 → Multiply all factors of 10
STEP 4 → Write final answer in scientific notation

Shortcut:
“One unit at a time + power rule = fast solution”

🧪 NEET Practice Questions - Unit Conversion & Dimensions

🟢 1. Direct MCQs (Single Correct Option)

Q1. 1 kg m² s⁻² is equal to:
A) 10⁵ g cm² s⁻²
B) 10⁷ g cm² s⁻²
C) 10⁶ g cm² s⁻²
D) 10⁸ g cm² s⁻²

Answer: B

Q2. 1 m is equal to:
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly

Answer: B

Q3. 3 m s⁻² equals:
A) 3.9 × 10³ km h⁻²
B) 3.9 × 10⁴ km h⁻²
C) 3.9 × 10⁵ km h⁻²
D) 3.9 × 10² km h⁻²

Answer: B

Q4. SI unit of G is:
A) N m² kg⁻²
B) kg m³ s⁻²
C) m² s⁻² kg
D) N m kg⁻²

Answer: A

🟡 2. Statement-Based Questions

Q5. Statement I: 1 m³ = 10⁶ cm³
Statement II: Volume depends on cube of length
A) Both true, II explains I
B) Both true, II not explanation
C) I true, II false
D) I false, II true

Answer: A

Q6. Statement I: 1 N = 1 kg m s⁻²
Statement II: Newton is derived unit
A) Both true, II explains I
B) Both true, II not explanation
C) I false, II true
D) I true, II false

Answer: A

🔴 3. Assertion & Reason

Q7.
A: 1 m² = 10⁴ cm²
R: Area depends on square of length
A) Both true, R explains A
B) Both true, R not explanation
C) A true, R false
D) A false, R true

Answer: A

Q8.
A: G has dimensions L³ M⁻¹ T⁻²
R: G = N m² kg⁻²
A) Both true, R explains A
B) Both true, R not explanation
C) A false, R true
D) A true, R false

Answer: A

🔵 4. Match the Columns

Column A	Column B
1 N	kg m s⁻²
1 m²	10⁴ cm²
1 J	kg m² s⁻²
1 kg	10³ g

Answer: A-2, B-1, C-3, D-4

🔥 5. Hard Questions

Q12. Convert 5 m s⁻² into km h⁻²
A) 5.4 × 10⁴
B) 6.2 × 10⁴
C) 4.8 × 10⁴
D) 3.6 × 10⁴

Answer: A

Q13. 1 m in light year:
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly

Answer: B

🧠 Exam Tips

✔ Convert stepwise
✔ Square and cube units carefully
✔ Use scientific notation
✔ Check final dimensions
✔ Avoid skipping steps

🧩 5. Concept Flow

Physical Quantity → Base Units (kg, m, s) → Derived Units (N, J, G) → Conversion Factors (10ⁿ) → Final Answer

🔥 6. Exam Strategy

✔ Convert step by step
✔ Always check power of units
✔ Use scientific notation
✔ Verify final dimensions
✔ Avoid skipping steps in NEET

🏆 Final Formula

Convert separately → Apply power → Multiply → Verify unit

Physics Constants Made Easy: Mnemonics, Tricks, Mind Maps & Memory Hacks

  Learn Physics Constants Fast with Mnemonics and Visual Memory Techniques

- Dr.Sanjaykumar Pawar 

🚀 Ultra-Memory Guide for Physics Constants

Instead of memorizing 20+ random numbers, group them into families, patterns, stories, and visual maps.

---

1. MASTER MEMORY TABLE

Constant	Value	Memory Trick
Electron Mass	9.11 × 10⁻³¹ kg	Electron = smallest → 9-11 emergency tiny particle
Proton Mass	1.67 × 10⁻²⁷ kg	Proton ≈ 1836 times heavier than electron
Neutron Mass	1.675 × 10⁻²⁷ kg	Neutron ≈ Proton
Electron Charge	1.6 × 10⁻¹⁹ C	Most important physics number
Speed of Light	3 × 10⁸ m/s	"3 followed by 8 zeros"
Planck Constant	6.626 × 10⁻³⁴	Triple 6 pattern
Gravitation Constant G	6.67 × 10⁻¹¹	G = 667
Avogadro Number	6.022 × 10²³	Mole's phone number
Boltzmann Constant	1.38 × 10⁻²³	Remember 138
Stefan Constant	5.67 × 10⁻⁸	Similar to Wien family
Wien Constant	2.898 × 10⁻³	Near 2.9
Solar Constant	1.366 × 10³	Sun sends 1366 W/m²
Sun Mass	1.989 × 10³⁰	Almost 2 × 10³⁰
Earth Mass	5.97 × 10²⁴	Almost 6 × 10²⁴
Earth Radius	6.4 × 10⁶ m	Easy approximation
Earth Density	5.5 × 10³ kg/m³	5.5
Earth Angular Velocity	7.29 × 10⁻⁵	Daily rotation
Earth-Moon Distance	3.84 × 10⁸ m	Nearly light-second
Earth Magnetic Moment	8.22 × 10²²	822
AU	1.496 × 10¹¹ m	Sun-Earth distance

---

 

Physics Constants Memory Map with Mnemonics, Tables and Visual Learning Techniques for Fast Exam Revision.

2. NUMBER FAMILY TRICK

Most physics constants belong to only a few number families:

Family A: 1.6

Think:

⚡ Charge of Electron

⚡ 1 eV

Both use:

1.6 × 10⁻¹⁹

Electron Charge
      ↓
    1.6
      ↓
    1 eV

---

Family B: 6.6

Think:

📌 Planck Constant

📌 Gravitational Constant

Planck → 6.626
Gravity → 6.67

Both start with 6.6

---

Family C: 6.0

Think:

🧪 Avogadro Number

6.022 × 10²³

Scientists love 6!

---

3. SUBATOMIC PARTICLE STORY

Imagine a family:

👶 Electron (tiny baby)

👨 Proton (big father)

👨‍🦳 Neutron (father's twin brother)

Electron = 9.11 ×10⁻³¹

Proton = 1.67 ×10⁻²⁷

Neutron = 1.675 ×10⁻²⁷

Memory:

"Proton and Neutron are twins."

Only remember one number:

1.67 × 10⁻²⁷

---

4. EARTH FAMILY TRICK

Everything about Earth revolves around 6.

Quantity	Value
Earth Mass	6 ×10²⁴
Earth Radius	6.4×10⁶
Density	5.5×10³

Mnemonic:

🌍 "Earth lives in House Number 6."

---

5. SUN FAMILY TRICK

Think:

☀ Sun is HUGE

Mass = 2 ×10³⁰ kg

Distance to Earth:

AU = 1.5 ×10¹¹ m

Mnemonic:

Sun weighs 2 and lives 1.5 away.

---

6. SPACE DISTANCE MEMORY CHAIN

Moon → Earth
3.84×10⁸ m

Sun → Earth
1.5×10¹¹ m

Light Year
9.46×10¹⁵ m

Visual ladder:

Moon
  ↓
10⁸

Sun
  ↓
10¹¹

Light Year
  ↓
10¹⁵

Every step jumps by about 10³–10⁴.

---

7. CONVERSION TRICKS

Conversion	Memory
1 Å	10⁻¹⁰ m
1 Fermi	10⁻¹⁵ m
1 eV	1.6×10⁻¹⁹ J
1 AU	1.5×10¹¹ m
1 Light Year	9.46×10¹⁵ m
1 HP	746 W

Tiny Length Ladder

Angstrom
10⁻¹⁰

↓ smaller

Fermi
10⁻¹⁵

Difference = 10⁵

---

8. SI BASE UNITS MEMORY SENTENCE

The 7 SI base units:

Quantity	Unit
Length	metre
Mass	kilogram
Time	second
Temperature	kelvin
Current	ampere
Amount	mole
Luminous Intensity	candela

Mnemonic:

"My King Takes Tea And Makes Cool Coffee"

My       → Metre
King     → Kilogram
Takes    → Time (second)
Tea      → Temperature
And      → Ampere
Makes    → Mole
Cool     → Candela
Coffee

---

9. QUICK EXAM CRAM SHEET

Must-Know Constants

c = 3×10⁸

e = 1.6×10⁻¹⁹

h = 6.626×10⁻³⁴

G = 6.67×10⁻¹¹

NA = 6.022×10²³

kB = 1.38×10⁻²³

Remember:

3, 1.6, 6.6, 6.0, 1.38

These five numbers solve most physics MCQs.

---

🧠 Mind Map

                    PHYSICS CONSTANTS
                           │
      ┌────────────────────┼────────────────────┐
      │                    │                    │
  Atomic               Universal             Earth
      │                    │                    │
 Electron             c=3×10⁸          Radius=6.4×10⁶
 Proton               h=6.626          Mass=6×10²⁴
 Neutron              G=6.67           Density=5.5×10³
 Charge=1.6           NA=6.022
                       kB=1.38
      │                    │
      └|────────────┬───────|Astronomy
    Constant                        │
     Plunk constant             AU=1.5×10¹¹
Gravitation constant            Moon=3.84×10⁸
Boltzmann Constant              Sun=2×10³⁰
Stefan Constant
Wien Constant
Solar Constant                  LY=9.46×10¹⁵
               
   

🎯 30-Second Revision Formula

Remember only:

3, 1.6, 6.6, 6.0, 1.38, Earth=6, Sun=2, AU=1.5

From these anchor numbers, most of the listed constants can be reconstructed during exams. 

INTERNAL LINKS

SI Units and Dimensional Analysis Explained

Complete Physics Formula Handbook

Motion and Kinematics Quick Revision Notes

Work, Energy and Power Formula Sheet

Electromagnetism Mind Maps and Memory Tricks

Modern Physics Notes for Competitive Exams

Thermodynamics Formula Cheat Sheet

Waves and Optics Revision Guide

Astronomy and Space Physics Basics

JEE Physics One-Page Revision Notes

Physics Constants & Units

A comprehensive memory toolkit designed to lock these physics constants, units, and conversion factors directly into your long-term memory using memory anchors, pattern-recognition tricks, and structural maps.

1. Master Reference Table (The Pattern Identifier)

Before diving into mnemonics, let's fix a subtle typo in your source list and organize these numbers by their powers of 10 to help your brain spot structural patterns.

Note: The speed of light (c) is accurately represented here as 3 × 10⁸ m/s for standard vacuum calculations.

Constant / Unit	Symbol	Value & Unit	The Pattern / Anchor Trick
Mass of Electron	me	9.109 × 10-31 kg	9-10-11 sequence (9.109 × 10-31)
Mass of Proton	mp	1.6726 × 10-27 kg	1.67 is standard; Proton has 2 (1.6726)
Mass of Neutron	mn	1.6749 × 10-27 kg	Neutron is heavier than proton; has 4 (1.6749)
Electron Charge	e	-1.602 × 10-19 C	Sweet 16 (1.6) and coming of age (19)
Speed of Light	c	3 × 108 m/s	Classic absolute constant.
Planck's Constant	h	6.626 × 10-34 J·s	6.6 and 3 halves to 4
Universal Gravitation	G	6.67 × 10-11 N·m²/kg²	6, 7, 11 (Convenience store numbers)
Avogadro's Number	NA	6.022 × 1023 mol-1	22nd of October (6.022 × 1023)
Boltzmann Constant	kB	1.38 × 10-23 J/K	1, 2, 3 sequence hidden: 1.38 × 10-23
Stefan's Constant	σ	5.67 × 10-8 W·m-2·K-4	Sequential count: 5, 6, 7, 8
Wien's Constant	b	2.898 × 10-3 m·K	Almost 3 × 10-3
Solar Constant	S	1.366 × 103 W·m-2	1366 (A year in history style)
Mass of Sun	Ms	1.989 × 1030 kg	Taylor Swift's album 1989
Mass of Earth	ME	5.97 × 1024 kg	Almost 6 × 1024
Radius of Earth	Re	6.4 × 106 m (or 6371 km)	64 Lakh meters
Density of Earth	ρ	5.513 × 103 kg/m³	Roughly 5.5 times water density (103)
Angular Velocity (Earth)	ω	7.29 × 10-5 rad/s	7.3 × 10-5
Astronomical Unit	AU	1.496 × 1011 m	Roughly 1.5 × 1011
Earth-Moon Distance	dem	3.844 × 108 m	38-44 pattern
Earth's Mag. Moment	M	8.22 × 1022 A·m²	Triple 2s and 8s

2. High-Impact Memory Mnemonics & Tricks

The Atomic Trio (Masses & Charge)

• Electron Mass (m_e = 9.1 × 10^-31): Notice the digit run. 9 point 1 × 10^-31. Think: "An electron is so light it fell down a 9 to 1 slide, all the way to -31."
• Proton (1.672 × 10^-27) vs. Neutron (1.674 × 10^-27): Both share 1.67 × 10^-27.
  • To remember which is heavier: Protons have 2 legs (1.672), Neutrons have 4 legs (1.674). A Neutron is always Noticeably heavier than a Proton.
• Electron Charge (-1.6 × 10^-19): Remember "Sweet 16 at 19". The value is 1.6, the power is -19.

The Astrophysics Quantities

• Stefan's Constant (σ = 5.67 × 10^-8): This is the easiest constant in physics because it counts sequentially: 5, 6, 7, 8.
• Universal Gravitational Constant (G = 6.67 × 10^-11): Think of the convenience store chain 7-Eleven. Roll back slightly to 6.67 and couple it with -11.
• Mass of the Sun (1.989 × 10³⁰): The Sun loves music. Its mass starts exactly with the year 1989 (1.989). The power is a round, hot 30.

3. Visual Concept Mapping

The Space Distance Ladder (From Smallest to Largest)

To remember distances and conversion coefficients intuitively, map them step-by-step out into space:

[ Earth ] 
    │
    ├─► Radius of Earth (Re) = 6.4 x 10⁶ m
    │
    ├─► Earth-Moon Distance = 3.84 x 10⁸ m (Same power of 10 as Speed of Light!)
    │
    ├─► 1 A.U. (Earth to Sun) = 1.496 x 10¹¹ m
    │
    └─► 1 Light Year (Interstellar) = 9.46 x 10¹⁵ m
        

Micro-Scale Distance Hierarchy

Use this visualization ladder to never mix up your microscopic conversions:

1 Meter ──► 1 Ångström (10⁻¹⁰ m) ──► 1 Fermi (10⁻¹⁵ m)
              [Atomic Scale]            [Nuclear Scale]
            

• Mnemonic: A comes before F in the alphabet, just like -10 comes before -15 on the number line.

4. SI Base Units Breakdown Chat Matrix

When navigating the fundamental systems of units (CGS, FPS, MKS, MKSA), you only need to look at the letters themselves to know what they measure:

[C]entimeter   [G]ram       [S]econd
[F]oot         [P]ound      [S]econd
[M]eter        [K]ilogram   [S]econd
[M]eter        [K]ilogram   [S]econd    [A]mpere
            

The 7 Fundamental Pillars of SI

Base Dimension	Unit Name	Symbol	Quick Brain Anchor
Length	metre	m	Standard stride
Mass	kilogram	kg	A liter of water
Time	second	s	Heartbeat pace
Temperature	kelvin	K	No degree symbol (°) allowed!
Electric current	ampere	A	Current flow
Amount of substance	mole	mol	Chemistry's dozen
Luminous intensity	candela	cd	Brightness of 1 standard candle

5. Instant Association Flash-Tricks

• 1 Horsepower = 746 Watts: Think of a mythical mechanical horse running down Route 746.
• 1 eV = 1.6 × 10^-19 J: You do not need to memorize this separately! It is exactly identical to the magnitude of the charge of an electron.
• Boltzmann Constant (k_B = 1.38 × 10^-23): Notice the pattern: 1, 2, 3. 1.38 × 10^-23. The digits 1, 2, and 3 are all present in the structural layout!