SHORT ANSWER TYPE QUESTION (3 MARKS EACH)
Q.1 Naphthalene balls disappear with time without leaving any solid give
reason.
Q.2 What is the effect of change of pressure on physical state of matter?
Explain with an example of gas.
Q.3 What is the relation between boiling point and the intermalecular forces
of attraction between the particles of a liquid? Explain giving example of
two liquids.
Q.4 Why is ice at 273k more effective in cooling than water at the same
temperature?
Q.5 Evaporation is known as surface phenomenon. Justify this statement.
Plz don't answer if you don't know.
I am in 9th class.
Subject :- Science.
Correct answer:- BRAINLIEST
Incorrect answer :- REPORT
And please answer fast..
Answers
Answer:
1.) Naphthalene balls disappear with time without leaving any solid because they undergo sublimation that is change of solid directly into gaseous state without changing into liquid state. Naphthalene balls are sublime substances .Their boiling point is very less.
2.) Change of pressure affects the physical state of matter. Increasing pressure and reducing temperature can liquefy gases.
Ex: Solid carbon dioxide is also called dry ice because it is directly converted into gaseous state by decreasing pressure to 1 atmosphere without coming into liquid state.
3.) There is a big relation of boiling point and intermolecular forces of attraction of liquid. As when we supply heat to any liquid to its boiling point the heat gets used in overcoming the force of attraction between its particles and hence the kinetic energy of particles increases and it gets converted into gases.
Ex: when we heat water 100 degree Celsius then we find that it's particles started boiling and converted to steam. this is all happen due to The Heat which overcomes the force of attraction of water molecules. in this way the kinetic energy of water molecules also increases and they started moving randomly and converted into steam.
4.) Ice at 273 K is more effective in cooling than water at the same temperature because ice will absorb the latent heat of fusion from its surrounding and get converted into water whereas no phase of change take place in the case of water. Due to absorption of heat energy from the surroundings Ice is more effective in cooling than water.
5.) Yes it is absolutely true that evaporation is known as a surface phenomena. It is because during evaporation liquid present on the surface has higher kinetic energy than rest liquid .Due to high kinetic energy they are able to overcome the force of attraction and hence they converted into vapour form. we know evaporation is a phenomenon of change of liquid into vapour at any temperature below its boiling point.
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