Tag: phase change

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Questions Related to phase change

Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

State True or False :
Evaporation or perspiration cools our body.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Evaporation or perspiration cools our body, it is true . Because molecules of sweat in perspiration , having higher kinetic energy and it goes out in the form of sweat, hence the average kinetic energy (internal energy) of molecules in sweat decreases, therefore, its temperature gets down and we feel cooler .

Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

When we dry our wet clothes in sun in a line then which phenomena applies to make them dry?

  1. Sublimation

  2. Fermentation

  3. Vaporisation

  4. Evaporation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Clothes are dried by evaporation due to heat from sunlight . In a line , clothes get sunlight for whole day , and due to heat from sun, rate of evaporation increases and clothes dry quickly .

Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change


Which is the final step of a water cycling driving small turbines before it is fed back into the primary pool?

  1. Evaporation

  2. Fermentation

  3. Sublimation

  4. Vaporisation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Evaporation is the final step of a water cycling driving small turbines before it is fed back into the primary pool. Water vapours are moving in the pipe at high speed under pressure exposed to turbine; which makes turbine rotate; left water vapour again condenses and go back in liquid state.

Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

What is not true about evaporation?

  1. Greater the surface area of the liquid, the quicker is the evaporation

  2. Evaporation produces cooling

  3. Evaporation takes place at all the temperatures

  4. Evaporation is nothing but boiling at the highest temperature of the liquid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Evaporization is the vaporization process of converting the liquid phase to vapour phase when surrounding temperature is more than liquid / water temperature.

It should not be confused with boiling as boiling means whole phase change from liquid to vapour at highest temperature.

Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

Statement-1
Evaporation takes place from the surface of a liquid.
Statement-2
The molecules at the surface have less attractive energy than those inside the liquid.

  1. Statement-1 is true, Statement-2 is true and Statement-2 is the correct explanation for Statement- 1

  2. Statement-1 is true, Statement-2 is true but Statement-2 is not the correct explanation for Staement-1

  3. Statement-1 is true, Statement-2 is false.

  4. Statement-1 is false, Statement-2 is true.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Evaporation is a surface phenomenon.
Particles present on the surface of a liquid only face attraction from one side (the side containing fluid particles) and surface tension. Where as particles inside the liquid would face attractive forces from all around, making it difficult for such particles to evaporate or escape.
Hence the statement is true, explanation is true and the explanation is the correct explanation for the statement.