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Ans 11 :- We know that evaporation causes cooling because of latent heat of vaporization .
So when water is sprinkled on the hot roof or an open ground after a hot sunny day , it evaporates , thus decreasing the temperature of the surroundings .
Ans 12 :- On a hot , humid day , due to the heat our body starts sweating for the cooling mechanism i.e., by evaporation and gets cooling effect . But the air cannot hold any more water on a humid day and therefore the sweat or perspiration is seen .
Ans 13 :- The temperature of the air inside balloon raises which increases the kinetic energy of the air particles makes them move fast and due to their movement the balloon bursts .
Ans 14 :- Any matter i.e., solid , liquid or gas when experiences an increase in temperature then they change their state .
In LPG cylinders , the petroleum gas is cooled and with lot of pressure changes it into liquid state .
Ans 15 :- The rate of evaporation depends on the following factors :-
1) Surface area : If the surface area is increased the rate of evaporation also increases.
For example
a) To dry the clothes we spread them to dry faster .
Ans 16 :- Camphor disappears after some time as its surface gains kinetic energy and directly gets converted into gas . The process of converting directly into gaseous form and not in a liquid state is termed as Sublimation . Hence , when camphor is given fire , it gets converted into gas and disappears , without leaving any residue .
Ans 17 :- When we touch ice we feel cold because of the melting and evaporation of the ice . When we touch the ice the ice quickly absorbs the heat of our hand , melts and evaporates with the heat . So we feel cold when we touch ice .
Ans 18 :- The amount of heat energy released or absorbed when a solid changing to liquid at atmospheric pressure at its melting point is known as the latent heat of fusion .
Ans 19 :- The amount of heat required to convert unit mass of liquid into vapour state without change in its temperature called is latent heat of vaporization .
Ans 20 :- Hence we feel cold .
When evaporation occurs then than the liquid ( mostly water ) absorbs all the heat from the surroundings and take it with it and we feel cool . Evaporation causes cooling effect because the heat energy is absorbed by surrounding particles .
Ans 21 :- We can justify table as a Solid as tables particles have high interparticle space between them .
Ans 22 :- In solid , force of attraction is high in liquid , force of attraction is moderate in gases , force of attraction is minimum .
Salt > Water > Oxygen