NCERT Most Important question & Solutions for class-9 Chapter-1 Matter in Our Surrounding (Chemistry) | Class-9 Science | EduGrown

NCERT Most Important question & Solutions for class-9 Chapter-1 Matter in Our Surrounding (Chemistry)

The start of class 9 marks the beginning of the foundation for class 11 and class 12. It is very important study the basics in order to understand each and every chapter properly. In this page, we have provided all the important question for cbse class 9 that could be asked in the examination. Students also need to study the ncert solutions for class 9 in order to gain more knowledge and understanding the lessons. Questions and Answers are way to learn the new things in a proper way. NCERT textbooks downloads for class 9 in pdf are also available for the students if they need more help. By downloading these books, they can study from it. Our experts also prepared revision notes for class 9 so that students should see the details of each and every chapters. Class 9 important questions are the best to revise all the chapters in the best way.

1. Arrange the three states of matter in the increasing order of: (i) rate of diffusion(ii) particle motion.
Answer
(i) Rate of diffusion: solid < liquid < gas.

(ii) Particle motion: solid < liquid < gas

2.Explain why heat energy is needed to melt a solid. Define latent heat of fusion.
Answer
Heat energy is needed to melt a solid because there exist forces of attraction between the particles of solid. The heat energy helps in overcoming the forces of attraction between the particles and thus helps in melting a solid.Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at atmospheric pressure at its melting point.

3.Why does the temperature remain constant during the change of state of matter? Explain it on the basis of change of solid state into liquid state.

Answer

The temperature remains constant as the heat gets used up in changing the state by overcoming the forces of attraction between the particles.For example, a solid melts on heating. Its temperature does not rise until the entire solid is converted into liquid. This heat energy gets hidden into the contents and is known as the latent heat.

4.List any four factors on which evaporation depends. Explain in short any three factors.

11. Convert the following temperature to Celsius scale:

(a) 300 K
► 300 K = (300 – 273)°C
= 27°C
(b) 573 K► 573 K = (573 – 273)°C
= 300°C

12.Why does our palm feel cold when we put some acetone or petrol or perfume on it?

ANSWERS

Acetone, petrol, and perfume evaporate at low temperatures. When some acetone, petrol, or perfume is dropped on the palm, it takes heat from the palm and evaporates, thereby making the palm cooler.

13.Give reason for the following observations.

(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.

Answer

(a) Naphthalene balls disappear with time without leaving any solid because of they undergoes sublimation easily i.e., the change of state of naphthalene from solid to gas takes place easily.

(b) Perfumes have high degree of vaporisation and its vapour diffuses into the air easily. Therefore, we can get the smell of perfume sitting several metres away.

14.Name A, B, C, D, E and F in the following diagram showing change in its state.

Answer

NCERT Quick Revision Notes For Chapter-1 Matter in Our Surrounding

NCERT Solution For Chapter-1 Matter in Our Surrounding

NCERT MCQs For Chapter-1 Matter in Our Surrounding