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I. Chapter Summary:

This chapter introduces the fundamental concept of matter—anything that has mass and occupies space. It explores the physical nature, states, and properties of matter, supported by scientific reasoning and daily life examples. The chapter discusses the three primary states of matter (solid, liquid, gas), and briefly touches on plasma and Bose-Einstein condensate as advanced states. Students learn about interconversion of states due to changes in temperature and pressure, latent heat, evaporation, and the factors affecting evaporation. The chapter builds a foundational understanding for all future chemistry topics.

II. Key Concepts Covered:

Concept	Description
Matter	Anything that has mass and occupies space. Exists in different states.
Physical Nature of Matter	Made up of particles; particles are very small and have space between them.
Characteristics of Particles	They are continuously moving and attract each other.
States of Matter	Solid (fixed shape & volume), Liquid (fixed volume, no fixed shape), Gas (no fixed shape or volume).
Interconversion of States	Matter changes state with change in temperature or pressure (melting, boiling, condensation, freezing, sublimation).
Latent Heat	Heat energy required to change the state of matter without changing its temperature.
Evaporation	Surface phenomenon where a liquid changes into vapour below boiling point.
Factors Affecting Evaporation	Surface area, temperature, humidity, wind speed.

III. Important Questions:

(A) Multiple Choice Questions (1 Mark):

1. Which of the following has the highest compressibility?
   a) Solid
   b) Liquid
   c) Gas ✅
   d) All of these
2. The smell of perfume spreads in a room due to:
   a) Evaporation
   b) Diffusion ✅
   c) Sublimation
   d) Conduction
3. The SI unit of temperature is:
   a) Celsius
   b) Fahrenheit
   c) Kelvin ✅
   d) Joule
4. Which one is not a factor affecting evaporation?
   a) Surface area
   b) Wind speed
   c) Humidity
   d) Volume of liquid ✅

(B) Short Answer Questions (2/3 Marks):

1. Why do solids have a definite shape and volume?
2. Why does a desert cooler cool better on a hot, dry day?
3. What is meant by latent heat of vaporization?
4. Explain why water kept in an earthen pot becomes cool during summer.
   – PYQ 2021

(C) Long Answer Questions (5 Marks):

1. Explain the different states of matter and their characteristics.
2. Define evaporation. Discuss the factors affecting the rate of evaporation.
3. Explain how increasing or decreasing pressure can change the state of matter.
4. Describe an activity to show that particles of matter are continuously moving.
   – PYQ 2022

(D) HOTS (Higher Order Thinking Skills):

1. Why does the temperature remain constant during melting and boiling even when heat is being supplied?
2. A person sweats more on a humid day than on a dry day. Explain why this happens.

IV. Key Formulas/Concepts:

Concept	Description
Latent Heat of Fusion	Amount of heat energy required to change 1 kg of solid into liquid at its melting point.
Latent Heat of Vaporization	Amount of heat energy required to change 1 kg of liquid into gas at its boiling point.
Kelvin to Celsius	°C = K – 273
Evaporation	A surface phenomenon; faster with high temp, low humidity, large surface area, fast wind.

V. Deleted Portions (CBSE 2025–2026):

 No portions have been deleted from this chapter as per the rationalized NCERT textbooks.

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026):

Unit/Chapter	Estimated Marks	Type of Questions Typically Asked
Matter in Our Surroundings	6–8 marks	Short answers, HOTS, MCQs, and activity-based reasoning

VII. Previous Year Questions (PYQs):

Year	Marks	Question
2021	3	Define latent heat and state its types with examples.
2022	5	Explain why evaporation causes cooling and list factors affecting it.
2019	2	Why does a gas exert pressure on the walls of its container?

VIII. Real-World Application Examples to Connect with Topics:

Concept	Real-World Application
Evaporation	Cooling of water in earthen pots, sweating in humans.
Diffusion	Fragrance of incense spreading, gases mixing in the atmosphere.
Change of States	Steam cooking, dry ice in fog machines, melting of butter.
Sublimation	Camphor and naphthalene balls disappearing over time.

IX. Student Tips & Strategies for Success:

 Time Management:

• Study theory in 25-minute sessions with 5-minute breaks.
• Focus on one subtopic per study session.

 Exam Preparation:

• Practice NCERT intext and exercise questions.
• Create flashcards for key terms and definitions.
• Revise with flowcharts and diagrams for interconversion of states.

 Stress Management:

• Practice concept-mapping and drawing diagrams to build understanding.
• Use real-life examples (like boiling water or ice) to link concepts.

X. Career Guidance & Exploration (Class 9–10 Specific):

Stream	Career Paths
Science	Chemist, Environmental Scientist, Physicist
Engineering	Chemical Engineer, Materials Scientist
Applied Fields	Meteorologist, Energy Analyst, Food Technologist

• Foundation Exams:
  • NTSE
  • Science Olympiads (NSO)
  • Vidyarthi Vigyan Manthan (VVM)
  • CBSE Science Challenge

XI. Important Notes:

•  Matter in Our Surroundings builds the foundation of Chemistry—revise it thoroughly.
•  Always use scientific terms (e.g., “inter-particle space,” “kinetic energy,” “diffusion”).
•  Practice labelled diagrams and write steps of activities clearly.
•  Refer to CBSE’s sample papers and competency-based question patterns for updated formats.