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The kinetic model of matter - class-X

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If, melting and boiling point of a liquid is $-{50}^{o}C$ and ${150}^{o}C$ respectively, and on the basis of this liquid a thermometer is formed with ${0}^{o}L$ representing the melting point as the minimum temperature on the scale and ${100}^{o}L$ representing the boiling point as the maximum temperature on the scale, find the melting and boiling point on this thermometer

  1. $0$ and ${100}^{o}L$ respectively

  2. ${30}^{o}L$ and ${80}^{o}L$ respectively

  3. ${20}^{o}L$ and ${70}^{o}L$ respectively

  4. ${25}^{o}L$ and ${75}^{o}L$ respectively


Correct Option: D

A constant pressure air thermometer gave a reading of 47.5 units of volume when immersed in ice cold water, and 67 units in a boiling liquids. The boiling point of the liquid will be

  1. $135^{0}$C

  2. $125^{0}$C

  3. $112^{0}$C

  4. $100^{0}$C


Correct Option: A

Freezing mixture is a mixture which produces very low temperature. State whether true or false.

  1. True

  2. False


Correct Option: A
Explanation:
Freezing mixture is a mixture which produces very low temperature. Statement is true.
Because it is a mixture of ice, water and salt or dry ice or alcohol which produces very low temperature.

Boiling is a surface phenomenon.

  1. True

  2. False


Correct Option: B
Explanation:
The statement is false, boiling is a surface phenomenon.
Actually, boiling is a bulk a phenomenon. Heat energy goes to the entire bulk of liquid and it starts boiling. Whereas evaporation is a surface phenomenon

When salt is properly mixed with ice, then melting point of ice 

  1. is lowered

  2. remains the same

  3. is raised

  4. becomes infinite


Correct Option: A
Explanation:
When salt is mixed with ice, then melting point of ice is lowered.
This is the fact due to which salt is used to melt ice on the rod in winter.

Fill in the blanks :

The ........................... of water is defined as the constant temperature at which water changes to steam.

  1. melting point

  2. boiling point

  3. saturation point

  4. all of the above


Correct Option: B
Explanation:

Answer is B

The constant temperature at which a liquid boils and turns to vapour is known as boiling point.

Boiling of liquid can take place at any temperature. 

  1. True

  2. False


Correct Option: B
Explanation:

The boiling point of a liquid is the temperature at which its vapor pressure is equal to the pressure of the gas above it.

Vaporization takes place at all temperatures.

The saturated vapour pressure of water at $100^\circ C$ is

  1. 750 mm of Hg

  2. 760 mm of Hg

  3. 76 mm of Hg

  4. 7.6 cm of Hg


Correct Option: B
Explanation:

Vapour pressure or equilibrium vapour pressure or saturated vapour pressure is defined as the pressure exerted by a vapour in thermodynamic equilibrium with condensed phase at given temperature. At $100^oC$, the vapour pressure is $1atm$; i.e. 760mm of Hg i.e. 76cm of Hg as $1mm=10^{-1}cm$.

The water can be made to boil even at $0$ if the pressure of surrounding is:

  1. 56 cm of Hg

  2. 5 cm of Hg

  3. 0.1 cm of Hg

  4. 4.6 mm of Hg


Correct Option: A
Explanation:
The water can be made to boil even at $0^\circ C$. 
As we know, the ideal equation for gases is $pV=nRT$. Now, if $V$ and $n$ are taken constants, $p=cT$, where $c$ is a constant.
So pressure is directly proportional to the temperature.
Water boils at $100^\circ C$ or $373K$ at $1atm$ pressure. So, to obtain boiling at $0^\circ C$ or $273K$, you need to reduce the pressure to $\dfrac {273\times 1}{373} atm = 0.732 atm=56\text{cm of Hg}$(approx).

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

  1. 1 cc

  2. 1000 cc

  3. 1500 cc

  4. 1670 cc


Correct Option: D
Explanation:

During change of state mass does not change.

Mass of water = 1gm
So mass of steam is also= 1gm
Density of steam =$0.0006gm/cm^3$
Initail volume of water =1$cm^3$(Density =$1gm/cm^3$) ($1=\dfrac { 1 }{ V } $) $,v=1cm^3$
Later volume of water converted to steam =$\dfrac { mass\quad of\quad steam }{ Density\quad of\quad steam } $
$=\dfrac { 1 }{ 0.0006 } $
$=\dfrac { 10000 }{ 6 } { cm }^{ 3 }$
$= 1670cm^3$
Change of volume = $1670cm^3$

On increasing the external pressure , the boiling point of liquid 

  1. is raised

  2. is lowered

  3. remain unaffected

  4. uncertain


Correct Option: A
Explanation:
On increasing the external pressure, the boiling point of liquid is increased.
Boiling point is the temperature at which vapor pressure of the liquid equals to the external pressure.
V.P, of liquid is a function of temperature.
Now, if we increase the external pressure, a higher temperature would be required so that V.P. equals to external pressure.

Rice takes longest time to cook

  1. at sea level

  2. at shimla

  3. at Mount Everest

  4. in a submarine 100 m below the surface of sea


Correct Option: C
Explanation:

At higher altitude, water starts boiling at lower temperature and heat required for cooking food is not available, because heat escapes in form of water vapour. So, rice takes longer time to cook at Mount Everest

Temperature at which liquid changes to gaseous state

  1. Freezing point

  2. Boiling point

  3. Neutral state

  4. None


Correct Option: B
Explanation:

boiling point is a temperature state when liquid state starts charging into gaseous state.

When 1 g of ice melts at $0^\circ C$

  1. 80 cal of heat is liberaed

  2. 80 cal of heat is absorbed

  3. no heat is required

  4. 160 cal heat is absorbed


Correct Option: B
Explanation:
For melting of $1g$ of ice $80cal$ of heat is required.
As latent heat of fusion for water is the heat required or released when $1g$ of ice melts into water or water changes into ice.

Latent heat of fusion for water $=80cal/g$

A piece of ice at $0$ is put into a vessel containing water at $0$ . The ice will

  1. melt

  2. not melt

  3. slightly melt

  4. vanish in no time


Correct Option: B
Explanation:
A piece of ice at $0^oC$ is put into a vessel containing water at $0^oC$ ice will not melt.
The ice will not melt because no heat will transfer as there is no temperature difference. And without that heat transfer is impossible.

Melting point of Aluminium is:

  1. $1000\ ^\circ C$

  2. $659\ ^\circ C$

  3. $1500\ ^\circ C$

  4. $100\ ^\circ C$


Correct Option: B
Explanation:

Melting point of Aluminium is $660.3^oC \approx (659^oC)$

Which of the following is true regarding a bucket of boiling water and a cup of boiling water.
I.The temperature of the two is the same.
II.The heat content of the two is the same.
III. The bucket of water contains more heat and is therefore hotter

  1. I only

  2. II only

  3. I and III only

  4. II and III only

  5. I, II and III only


Correct Option: A
Explanation:

The water is boiling In bucket and in cup, we have same liquid in bucket and cup, the water ,since the boiling point of water is  $100^{o}C$ therefore temperature is same in both .

The heat given $\Delta Q$ to the mass $m$  of substance to raise the temperature by $\Delta \theta$  is 
                          $\Delta Q=mc\Delta\theta$    where  $c$  is the specific heat of substance
The mass of water in bucket is larger therefore it has larger heat content by above relation. 
               now        $\Delta\theta=\Delta Q/mc$ 
The bucket of water contains more heat but on the other hand it also has larger mass ,therefore $\Delta Q/m$ is constant for both and hence both are at same temperature  
                          $\Delta\theta=\Delta Q/mc$ 
 here, $c$ is constant because both pots have same liquid (water) .

In pressure cookers the boiling point of water increases due to the __________  created by blocking of the steam by weight.

  1. temperature

  2. moisture

  3. heat

  4. pressure


Correct Option: D
Explanation:

The boiling point of any liquid increases by exerting pressure on it. In a pressure cooker, the whistle applies pressure because of its weight.

The melting point of ice can be given by:

  1. $32\ ^\circ F$

  2. $32 \ ^\circ C$

  3. $273.15\ K$

  4. Both a and c


Correct Option: D
Explanation:

The relation between Celsius and Fahrenheit is given by $\dfrac C{100} = \dfrac{F - 32} {180}$ 

The relation between Celsius and Kelvin is given by, $K = C + 273.15$
So, melting point of ice $=0^oC=32^oF=273.15K$

Boiling point of water at normal atmospheric pressure is ______.

  1. $0^{\circ}C$

  2. $100^{\circ}C$

  3. $110^{\circ}C$

  4. $-4^{\circ}C$


Correct Option: B
Explanation:

The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. The boiling point of liquids varies with and depends upon the surrounding environmental pressure. 

The normal boiling of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level i.e., at 1 atmosphere (atm) is $100^0C$.

The melting point of mercury is:

  1. $38.8\ ^\circ C$

  2. $-38.8\ ^\circ C$

  3. $4250\ ^\circ C$

  4. $452\ ^\circ C$


Correct Option: B
Explanation:

Melting point of mercury is $-38.83^oC$

Water at normal atmospheric pressure boils at :

  1. $0^{\circ}C$

  2. $100^{\circ}C$

  3. $250\ K$

  4. $50^{\circ}C$


Correct Option: B
Explanation:

Boiling occurs when the vapor pressure exceeds the surrounding pressure from the atmosphere. At standard atmospheric pressure, water boils at approximately $100^0 C$.

Boiling point of water at normal atmospheric pressure is ____________

  1. ${0}^{o}C$

  2. ${100}^{o}C$

  3. ${110}^{o}C$

  4. ${-5}^{o}C$


Correct Option: B
Explanation:

Boiling point of water at normal atmospheric pressure is $100^oC$

The temperature of boiling water in the Kelvin scale of temperature is:

  1. $100$ K

  2. $373.15$ K

  3. $212$ K

  4. $273.15$ K


Correct Option: B
Explanation:

The relation between Celsius and Kelvin is given by, $K = C + 273.15$

So, temperature of boiling water $=100^oC=100+273.15K=373.15K$

Cooking takes longest time

  1. At the sealevel

  2. At Simla

  3. At Mount Everest

  4. In a submarine 100 m below the surface of water


Correct Option: C

Normallly the body temperature of healthy person is ______ Degree celcius?

  1. 25

  2. 37

  3. 30

  4. 32


Correct Option: B
Explanation:
Normally the body temperature of healthy person is $37^oC$ or ($98.6^oF$)
It is scientific fact that normal body temperature of a healthy body is $37^oC$. Apparently it is the perfect balance as it's warm enough to prevent fungal infection but not so hot that we need to eat non-stop to maintain out metabolism.

Water in a lake is changing into ice at $0^{o}C$. When the atmospheric temperature is $10^{o}C$. If the time taken for $1\ cm$ thick ice layer to be formed is $7$ hour, the time required for the thickness of ice to increase from $1\ cm $ to $2\ cm$ is

  1. $7\ hour$

  2. $14\ hour$

  3. $<7\ hour$

  4. $>14\ hour$


Correct Option: B

25 degree celcius is equal to ?

  1. 77 Fahrenheit

  2. 85 Fahrenheit

  3. 100 Fahrenheit

  4. 120 Fahrenheit


Correct Option: A
Explanation:
For converting $^oC$ in $^oF$, we know by formula:
$F=\cfrac{9}{5}C+32$
For $25^oC$,
$F=\cfrac { 9 }{ 5 } \times 25+32=45+32=77℉\\ 25℃=77℉$

How much heat energy is gained when 5 kg of water at  $20 ^ { \circ } \mathrm { C }$ is brought to its boiling point?

  1. 1680 KJ

  2. 1700 KJ

  3. 1720 KJ

  4. 1740 KJ


Correct Option: A
Explanation:

$Q = mc\Delta \theta $

$ = 5 \times \left( {1000 \times 4.2} \right) \times \left( {100 - 20} \right)$
$ = 1680 \times {10^3}J$
$ = 1680\,KJ$
Hence,
option $(A)$ is correct answer.

The melting point and the boiling point of oxygen is:

  1. negative

  2. positive

  3. zero

  4. none of these


Correct Option: A

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

  1. $1\;cc$

  2. $1000\;cc$

  3. $1500\;cc$

  4. $1670\;cc$


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?

  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


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

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

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

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

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


Correct Option: C

State whether true or false:

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

  1. True

  2. False


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 :

  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


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.

  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


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?

  1. $819^oC$

  2. $719^oC$

  3. $909^oC$

  4. None of these


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?

  1. Sir Isaac Newton

  2. Daniel Bernouili

  3. James Clerk Maxwell

  4. Cound Rumford


Correct Option: B

Existence of force of attraction between a body and earth is______

  1. real force

  2. pseudo force

  3. gravitational force

  4. elector magnetic force


Correct Option: C
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