Chapter 1: Matter in Our Surroundings- Exercise- 3

Science

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Chapter 1: Matter in Our Surroundings

Class: IX

Exercise  3

Question 1

Convert the following temperature to Celsius scale:

1. a) 300 K
2. b) 573 K

Answer 1

1. a) (300 − 273)°C = 27°C
2. b) (573 − 273)°C = 300°C

Question 2

What is the physical state of water at:

1. a) 250°C
2. b) 100°C

Answer 2

1. a) At 250°C - Gaseous state.
2. b) At 100°C - both liquid and gaseous form.

 At this temperature, water starts changing from liquid state to gaseous state, when it gets the heat equal to the latent heat of vaporization.

Question 3

For any substance, why does the temperature remain constant during the change of state?

Answer 3

The temperature remains constant during a change of state. This is because all the heat supplied to increase the temperature is utilized (as latent heat) to overcome the forces of attraction between the particles and thereby change of state. Therefore, this heat does not use for increasing the temperature of the substance.

 

Question 4

Suggest a method to liquefy atmospheric gases.

Answer 4

By reducing the temperature and applying pressure, atmospheric gases can be liquefied.