Q8. Give the characteristics of the particles of matter.
Q9. Water droplets seen on the outer surface of a glass containing ice-cold water .Name the process and state
cause.
Q10. What is the difference between evaporation and boiling .
Q11. Define Latent heat of vaporization.
Q12. Explain why temperature remains constant during the change of state of any substance?
Q13. Define sublimation with examples.
Q14. Do we sweat more on a dry day or humid day? Justify your reason.
Q15. Why do we see water droplets on the outer surface of a glass containing ice cold water?
Answers
1. The characteristics of particles of matter are:
- All matter is composed of very small particles which can exist independently.
- Particles of matter have spaces between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
2. Condensation can also produce water droplets on the outside of soda cans or glasses of cold water. When warm air hits the cold surface, it reaches its dew point and condenses. This leaves droplets of water on the glass or can. When a pocket of air becomes full of water vapor, clouds form.
3. To summarize, evaporation is slower, occurs only from the surface of the liquid, does not produce bubbles, and leads to cooling. Boiling is faster, can occur throughout the liquid, produces lots of bubbles, and does not result in cooling.
4. The enthalpy of vaporization, also known as the heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas. The enthalpy of vaporization is a function of the pressure at which that transformation takes place.
5. The temperature remains constant during the change of state because the heat energy which is supplied to change the state of matter is used in breaking the intermolecular forces and other attractive forces. ... Hence the temperature remains constant as all the heat is used up and no external heat is released or absorbed.
6. Sublimation is the process by which a substance changes from solid state directly to vapour state. Example : dry ice, naphthalene balls etc.
7. ▶On a dry day, the sweat is evaporated due to dry weather and our body feels cool but on a humid day, the sweat doesnot evaporate because of the presence of moisture in air. ▶Therefore our body remains hot and we sweat even more. ▶Hence, sweating is more on a humid day than a dry day.
8. Dew point is the temperature at which condensation happens. ... Condensation can also produce water droplets on the outside of soda cans or glasses of cold water. When warm air hits the cold surface, it reaches its dew point and condenses. This leaves droplets of water on the glass or can.