SEBA Class 9 Science Important Chapter 1 Matter in Our Surroundings

SEBA Class 9 Science Important Chapter 1 Matter in Our Surroundings Solutions English Medium As Per SEBA New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters SEBA Class 9 General Science Additional Solutions and select need one. NCERT Important Solutions For Class 9 General Science Download PDF. Important Notes for Class 9 Science.

SEBA Class 9 Science Important Chapter 1 Matter in Our Surroundings

Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. Assam SEBA Board Class 9 Science Additional Question Answer are part of All Subject Solutions. Here we have given CBSE Class 9 Science Important Notes for All Chapters, You can practice these here.

Matter in Our Surroundings

Chapter: 1

IMPORTANT QUESTION ANSWER

Answer the following Questions:

1. What does matter?

Ans: Matter is anything that occupies space and has mass.

2. Name the three states of matter.

Ans: Solid, liquid, and gas.

3. Define boiling point.

Ans: The temperature at which a liquid changes into gas at atmospheric pressure.

4. What is the SI unit of temperature?

Ans: Kelvin (K).

5. What is the melting point of ice?

Ans: 273.15 K or 0°C.

6. Why do solids have a definite shape and volume?

Ans: Solids have tightly packed particles with strong force of attraction between them. The particles only vibrate in place, giving solids a fixed shape and volume.

7. Why is ice at 0°C more effective in cooling than water at 0°C?

Ans: Because ice absorbs additional heat in the form of latent heat of fusion without a rise in temperature. This extra absorption makes it more effective in cooling.

8. List three characteristics of particles of matter.

Ans: (i) Particles of matter have space between them.

(ii) Particles are continuously moving.

(iii) Particles attract each other.

9. Define diffusion with an example.

Ans: Diffusion is the intermixing of particles of two different substances on their own.

Example: Smell of perfume spreading in a room.

10. Explain the process of sublimation with examples.

Ans: Sublimation is the process where a solid directly changes into gas without becoming liquid.

Examples: Camphor, Naphthalene balls.

11. What is latent heat of fusion?

Ans: It is the amount of heat energy required to convert 1 kg of a solid into liquid at its melting point without changing its temperature.

12. Write three differences between boiling and evaporation.

Ans: 

Boiling	Evaporation
(i) At fixed temperature.	(i) At all temperatures.
(ii) Occurs throughout the liquid.	(ii) Occurs only at the surface.
(iii) Rapid process.	(iii) Slow process.

13. List four factors affecting the rate of evaporation.

Ans: (i) Surface area.

(ii) Temperature.

(iii) Wind speed.

(iv) Humidity.

14. How does evaporation cause cooling?

Ans: Evaporation causes cooling because the particles of a liquid absorb heat from their surroundings to change into vapour. This absorption of heat lowers the temperature of the surroundings. For example, when acetone or perfume is applied to the skin, it feels cool as the liquid takes heat from the skin to evaporate. Similarly, sweating cools the body because the sweat absorbs body heat during evaporation. Thus, evaporation results in cooling.

15. Why do we see water droplets on the outer surface of a glass containing ice-cold water? 

Ans: We see water droplets on the outer surface of a glass containing ice-cold water because the water vapour present in the air comes in contact with the cold surface of the glass. On cooling, this vapour loses its energy and condenses into liquid water. This process is called condensation. As a result, small droplets of water appear on the outer surface of the glass.