Page 23 - Understanding NCERT Science 09

Exercises

1. Convert the following temperatures to the celsius scale.
(a) 293 K (b) 470 K
2. Convert the following temperatures to the kelvin scale.
(a) 25 °C (b) 373 °C
o
o
3. 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.
4. Arrange the following substances in increasing order of forces
of attraction between the particles— water, sugar, oxygen.
5. What is the physical state of water at—
o
(a) 25 °C (b) 0 °C (c) 100 °C ?
o
o
6. Give two reasons to justify—
(a) water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.
7. Why is ice at 273 K more effective in cooling than water at the
same temperature?
8. What produces more severe burns, boiling water or steam?
9. Name A,B,C,D,E and F in the following diagram showing
change in its state

12 SCIENCE

Rationalised 2023-24