1. What is Matter?
Matter is anything that has mass and occupies space (volume).
Examples:
Examples:
- Water, air, rocks, metals, wood, your body – all are matter.
- Things we can see and touch.
हिंदी: Matter = वह सब चीज़ें जिनका द्रव्यमान होता है और जो जगह घेरती हैं –
जैसे पानी, हवा, लोहे की छड़, किताब, मेज़, हमारा शरीर आदि।
लेकिन भावना, खुशी, दुख, रोशनी, आवाज़ – ये matter नहीं, energy हैं।
2. Particle Nature of Matter
Key ideas:
- Matter is made up of very tiny particles (atoms / molecules).
- There are spaces between these particles.
- Particles of matter are in continuous motion.
- Particles attract each other with some force.
हिंदी Summary:
छोटे-छोटे कण + उनके बीच जगह + लगातार गति + आपस में आकर्षण
→ यही चार बातें matter के behaviour को समझाती हैं।
3. States of Matter – Solid, Liquid, Gas
Traditionally three main states:
- Solid
- Liquid
- Gas
3.1 Solids
Properties:
- Definite shape and definite volume.
- Particles are very closely packed (least intermolecular space).
- Particles vibrate about fixed positions.
- Strong force of attraction between particles.
हिंदी: Solids = फिक्स shape + फिक्स volume –
कण बहुत पास-पास, आकर्षण बहुत ज़्यादा → shape आसानी से नहीं बदलता।
3.2 Liquids
Properties:
- No fixed shape, but fixed volume.
- Take the shape of the container.
- Particles are less tightly packed than solids.
- Particles can slide past each other → liquids can flow.
हिंदी: Liquids = shape बदलती है, volume स्थिर रहता है –
जिस बर्तन में डालो, उसका shape ले लेते हैं। flow कर सकते हैं।
3.3 Gases
Properties:
- No fixed shape, no fixed volume.
- Completely fill the container in which they are placed.
- Particles are far apart, move randomly at high speed.
- Very weak force of attraction between particles.
हिंदी: Gases = ना shape fix, ना volume fix –
पूरा बर्तन भर लेते हैं; कण बहुत दूर-दूर और तेज़ गति से इधर-उधर घूमते हैं।
4. Change of State – Melting, Boiling, Condensation
States of matter can change when we heat or cool a substance.
- Melting / Fusion: Solid → Liquid (e.g., ice → water).
- Freezing / Solidification: Liquid → Solid (water → ice).
- Boiling / Vaporisation: Liquid → Gas (water → steam).
- Condensation: Gas → Liquid (steam → water).
- Sublimation: Solid → Gas directly (e.g., camphor, naphthalene).
हिंदी: Heat देने या निकालने से state बदलती है –
गर्मी → ice पिघलकर पानी, पानी उबलकर भाप
ठंड → भाप से पानी, पानी से फिर ice
5. Diffusion (Very NDA-Friendly Concept)
Diffusion = Mixing of particles of two substances on their own.
- Fastest in gases (e.g., smell of perfume spreads quickly in a room).
- Slower in liquids; slowest in solids.
हिंदी: Diffusion = दो पदार्थों के कणों का अपने आप मिल जाना –
जैसे अगर एक कोने में perfume छिड़को, तो थोड़ी देर में पूरी room में smell फैल जाती है।
6. Simple Comparison Table
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Definite | No definite (takes container’s shape) | No definite |
| Volume | Definite | Definite | No definite (fills container) |
| Particle arrangement | Very close | Less close | Far apart |
| Movement | Vibrate in fixed positions | Slide over each other | Move freely, randomly |
| Force of attraction | Strong | Moderate | Very weak |
हिंदी: Table को 2–3 बार revise करेंगे तो Solids–Liquids–Gases का concept NDA level के लिए पूरा clear हो जाएगा।
📘 Practice Questions (NDA Style)
1. Matter is anything that:
a) Has mass only
b) Occupies space only
c) Has mass and occupies space
d) Produces light
2. Which of the following is NOT matter?
a) Air
b) Water
c) Sound
d) Iron rod
3. In which state of matter are particles closest to each other?
a) Solid
b) Liquid
c) Gas
d) Plasma
4. Which of the following changes is an example of sublimation?
a) Ice → water
b) Water → steam
c) Camphor → vapour
d) Steam → water
5. The spreading of the smell of perfume in a room is an example of:
a) Melting
b) Boiling
c) Diffusion
d) Condensation
a) Has mass only
b) Occupies space only
c) Has mass and occupies space
d) Produces light
2. Which of the following is NOT matter?
a) Air
b) Water
c) Sound
d) Iron rod
3. In which state of matter are particles closest to each other?
a) Solid
b) Liquid
c) Gas
d) Plasma
4. Which of the following changes is an example of sublimation?
a) Ice → water
b) Water → steam
c) Camphor → vapour
d) Steam → water
5. The spreading of the smell of perfume in a room is an example of:
a) Melting
b) Boiling
c) Diffusion
d) Condensation
Answers:
1 – c) Has mass and occupies space
2 – c) Sound
3 – a) Solid
4 – c) Camphor → vapour
5 – c) Diffusion
1 – c) Has mass and occupies space
2 – c) Sound
3 – a) Solid
4 – c) Camphor → vapour
5 – c) Diffusion
Quick Recap | सार
Now you should be able to:
- Recall the most important ideas of this topic.
- Solve typical NDA-style questions from this chapter.
- Spot and avoid common traps used in competitive exams.
Self-check: 3–4 random questions उठा कर देखिए – अगर आसानी से हो रहे हैं, तो chapter strong है।
Common Exam Mistakes | आम गलतियाँ
- Concept ठीक से clear न करना और सीधे रटने की कोशिश करना।
- Question पूरी तरह पढ़े बिना answer mark कर देना।
- Figures, dates, या formulas को last step में verify न करना।
NDA में smart strategy यह है कि आसान वाले सवाल पहले, doubtful बाद में – और silly mistakes से बचना सबसे ज़रूरी है।