Tag: change of states

Questions Related to change of states

When $1\;g$ of water at $100^{\circ}C$ gets converted into steam at the same temperature, the change in volume is approximately :

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. $1\;cc$

  2. $1000\;cc$

  3. $1500\;cc$

  4. $1670\;cc$

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Correct Option: D
Explanation:

Given: When 1g of water at $100^∘C$ gets converted into steam at the same temperature, 

To find the change in volume
Solution:
We know, 
Density of water, $\rho=1000kg/m^3=1 g/cm^3$
Density of steam, $\rho=0.6kg/m^3=0.0006 g/cm^3$
Mass of the water and mass of water, $m=1g$
Volume of water is
$m=\rho V\\implies V=\dfrac m\rho=\dfrac 11\\implies V=1cc$
Volume of steam, 
$V'=\dfrac m\rho=\dfrac 1{0.0006}=1666.7cc\approx1667cc$
The change in volume, 
$\Delta V=V'-V\\implies \Delta V=1667-1=1666cc$

 Identify what happens to the temperature of water as it boils?

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. It remains constant

  2. It continues to increase as long as heat is applied

  3. It increases only if the amount of heat applied is increased

  4. temperature and heat are not realted

  5. temperature and heat are related but not the same

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Correct Option: A
Explanation:

Temperature of a substance during its phase change remains constant. Hence when water boils, the temperature of water remains constant  i.e  $100^oC$.

boiling point of petrol

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. ${ 10 }^{ o }-{ 25 }^{ o }$

  2. $ { 120 }^{ o }-{ 180 }^{ o }C$

  3. $ { 30 }^{ o }-{ 120 }^{ o\quad }C$

  4. ${ 100 }^{ o }-{ 270 }^{ 0 }C$

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Correct Option: C

State whether true or false:

Dew point is the temperature at which the gas at given atmospheric conditions becomes saturated.

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. True

  2. False

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Correct Option: A
Explanation:

The dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates so dew point is a temperature at which the air becomes saturated.

A fan produces a feeling of comfort because :

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. A fan supplies cool air

  2. Of the evaporation of sweat

  3. Fan increases the humidity in air

  4. Fan decreases the humidity in air

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Correct Option: B
Explanation:

A fan produces a feeling of comfort because of evaporation of sweat. As evaporation releases heat energy, and evaporation of sweat. Results in feeling cool in those body parts.

Define intermolecular force of attraction.

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. The force of attraction between the electrons and protons of an atom is called the intermolecular force of attraction.

  2. The force of attraction between the molecules of matter is called the intermolecular force of attraction.

  3. The force of attraction between the elements in a molecule is called the intermolecular force of attraction.

  4. None of the above

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Correct Option: B
Explanation:

The force of attraction between the molecules of matter is called the intermolecular force of attraction.

At what temperature rms speed of air molecules is doubled of that at NTP?

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. $819^oC$

  2. $719^oC$

  3. $909^oC$

  4. None of these

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Correct Option: A
Explanation:

$v _{rms}\propto \sqrt{T}$
$\Rightarrow \displaystyle\frac{v^2 _1}{v^2 _2}=\frac{T _1}{T _2}$
$\Rightarrow \displaystyle\frac{v^2}{4v^2}=\frac{273}{T _2}$
$\Rightarrow \displaystyle T _2=1092K$
$=819^oC$

He was a pioneer in the kinetic theory of gases. He contributed a lot to the fluid mechanics and the theory of vibrating strings. Who is this founder of mathematical physics?

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. Sir Isaac Newton

  2. Daniel Bernouili

  3. James Clerk Maxwell

  4. Cound Rumford

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Correct Option: B

Existence of force of attraction between a body and earth is______

physics the kinetic model of matter force and kinetic theory change of states phase change

  1. real force

  2. pseudo force

  3. gravitational force

  4. elector magnetic force

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Correct Option: C