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

Rate of evaporation increases 

  1. with the rise in temperature

  2. with the fall in temperature

  3. irrespective of temperature

  4. only beyond room temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rate of evaporation Increases with the rise in temperature as increasing temperature increases the kinetic energy of molecules of the liquid which facilitates the molecule to convert into vapour.

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

Water evaporates under atmospheric pressure. Without changing the temperature, the same water is placed under partial vacuum. The rate of evaporation _________.

  1. increases

  2. drop to zero

  3. decreases

  4. remain unaffected
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In partial pressure, the pressure is less;
According to Le-chatlier's principle on decreasing pressure; volume increases, so more water into gas(vapour)
So, rate of evaporation increases.
Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

From the following which are the factors affecting the rate of evaporation?

  1. Temperature

  2. Humidity

  3. Exposed Surface Area

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

1. Temperature - If we increase the temperature of a liquid, its molecules get more kinetic energy and more molecules will come out rapidly from the surface of liquid i.e. rate of evaporation increases.


2. Humidity - Humidity is measurement of amount of vapour present in air. If humidity is high, it will be difficult for liquid to add more vapour in air as there is already high amount of vapour, therefore with increase in humidity, rate of evaporation decreases and vice- versa.


3. Exposed surface area - If exposed surface area is increased, more liquid molecules come on the surface, as evaporation is a surface process, therefore rate of evaporation increases.

Hence, all these factors affect the rate of evaporation.
Multiple choice physics the kinetic model of matter evaporation heat, internal energy and work phase change

State True or False :
Evaporation takes place at all temperatures.

  1. True

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

True, Evaporation takes place at any temperature. When the air molecule strike the surface, they are going to impart some energy to water molecules. If this energy is sufficient enough to change the phase of water molecules; we experience a phenomenon evaporation. It can occur at any temperature.