Matter in our surroundings – Class IX – In-text Solution (Part 3)

(Answers of In-text Question in NCERT Science Text Page 9)

1. Convert the following temperature to Celsius scale.

(Temperature on Celsius scale = Temperature of Kelvin scale – 273)

(a) 300 K

Ans : 300 Kelvin (K) – 273 = Temperature in Celsius = 27⁰C

(b) 573 K

Ans : 573 Kelvin (K) – 273 = Temperature in Celsius = 300⁰C

2. What is the physical state of water at

(a) 250⁰C

Ans: Water boils at 100⁰C and therefore the physical state of water at 250⁰C is gaseous (water vapour).

(b)100⁰C

Ans: Since, the water boils at 100⁰C, thus at 100⁰C water is in transition phase, therefore the water at 100⁰C is in both liquid and gaseous state.

3. For any substance why does the temperature remain constant during the change of state.

Ans:  During the change of state of any substance, the heat supplied or released is utilised in the phase change. Such heat is called latent heat. So, the temperature of any substance remains constant during the change of state.

4. Suggest a method to liquefy atmospheric gas.

Ans: Atmospheric gas can be liquefied by increasing pressure and decreasing temperature.