please give me answers only!
class 9
cbsc
chapter 1
Answers
Answer:
The ans is as follows:
Explanation:
1. a) It is the amount of heat energy that is required to change 1 kg of solid into liquid at atmospheric pressure at its melting point.
b) It is the amount of heat that is required to change 1 kg of liquid into gas at atmospheric pressure at it's boiling point.
2. IDK
3. It floats on water cuz it is more dense. when water molecules freeze then the hydrogen bonds strengthen and push the other water molecules farther away. hence the space b/w the molecules increases.
4. Physical state of water at 250° will be gas (vapours)
Physical state if water at 100° will be liquid and gas (both) cuz it is the boiling point.
Physical state of water at 0° will be liquid and solid
5. I) idk
ii) steam has more energy than boiling water cuz it possesses latent heat of vaporization. and hence the burns caused are more severe .
6. these r the forces of mediate interaction b/w molecules . they include Forces of attraction and repulsion
7. yes, by high pressure and low temp.
5 marker ques
1. a) the phenomenon by which molecules in liquid statundergo a impulsive transition to the gaseous phase at any temp below it boiling point is called evaporation.
FACTORS:
- temperature
- surface area
- humidity
- wind speed
b) the particles of liquid absorb energy from the surroundings to overcome the interparticle forces of attraction and undergo a phase change. this causes a cooling affect.
2. ans in the pic
3. MELTING POINT : The melting point of a solid is defined as the temp at which the solid melts to become a liquid
BOILING POINT : It is defined as the temp at which the vapour and pressure of the liquid is equal to the atmospheric pressure.
FREEZING POINT : Temp at which liquid turns to solid when cooled.
Mitochondria is the powerhouse of the cell.