Tag: physics

Questions Related to physics

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

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

  1. $100$ K

  2. $373.15$ K

  3. $212$ K

  4. $273.15$ K

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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

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

  1. At the sealevel

  2. At Simla

  3. At Mount Everest

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

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Correct Option: C

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

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

  1. 25

  2. 37

  3. 30

  4. 32

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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

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

  1. $7\ hour$

  2. $14\ hour$

  3. $<7\ hour$

  4. $>14\ hour$

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Correct Option: B

25 degree celcius is equal to ?

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

  1. 77 Fahrenheit

  2. 85 Fahrenheit

  3. 100 Fahrenheit

  4. 120 Fahrenheit

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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?

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

  1. 1680 KJ

  2. 1700 KJ

  3. 1720 KJ

  4. 1740 KJ

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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:

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

  1. negative

  2. positive

  3. zero

  4. none of these

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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 :

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. $1670\;cc$

Show answer
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