Tag: heat, internal energy and work

Questions Related to heat, internal energy and work

In our daily chores when we mop our house floor then it becomes dry after some time. Which phenomena applies here?

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

  1. Fermentation

  2. Sublimation

  3. Vaporisation

  4. Evaporation

Show answer
Correct Option: D
Explanation:

Our floor get wet due to mopping , and after some time water droplets are evaporated and floor become dry .



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

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

  1. Evaporation

  2. Fermentation

  3. Sublimation

  4. Vaporisation

Show answer
Correct Option: A
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.


State True or False :

A puddle on the road dries out after some while in sun due to fermentation.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

A puddle on the road dries out after some time due to evaporation, not due to fermentation . 

Fermentation is a chemical breakdown of a substance by microorganism (bacteria , yeast etc.) .

State True or False :
Evaporation phenomena is used when we dry our hair with hair dryer. 

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

When we dry our hair , evaporisation takes place , as water droplets in hair are evaporated by air . The given statement is true .

What is not true about evaporation?

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

  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

Show answer
Correct Option: D
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.

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.

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

  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.

Show answer
Correct Option: A
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.

Which of the following statement is wrong ?

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

  1. At room temperature evaporation of water is rapid as compared to ethanol

  2. Water is more viscous as compared to ethanol

  3. Liquid drops are spherical in shape

  4. Clothes are easily dried in dry day as compared to humid days

Show answer
Correct Option: A,B
Explanation:

A: At room temperature evaporation of ethanol is rapid as compared to water. Hence, A is incorrect. 

B: water is more viscous compared to ethanol, hence statement is true. 
C: liquid drops are spherical due to surface tension of liquid drop,hence statement is true.
D: Clothes are dried easily as it is less humid on dry day,hence statement is true.