Physics

Thermodynamics and Gas Laws

616 Questions

Thermodynamics and gas laws questions test the understanding of ideal gas behavior, work done during thermodynamic processes, and specific heat ratios. Key areas include isothermal, adiabatic, and isobaric expansions along with real gas deviations. These mathematical physics concepts are standard in engineering and general science competitive exams.

Ideal gas equationIsothermal and adiabatic processesThermodynamic workGas kinetic theoryReal gas behavior

Thermodynamics and Gas Laws Questions

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

The mean free path of a gas varies with absolute temperature as :

  1. T
  2. T$^{-1}$
  3. T$^2$
  4. T$^4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The expression for mean free path $\lambda =\dfrac { RT }{ \sqrt { 2 } \pi { d }^{ 2 }NP } $ mean free path is directly proportional to Temperature

Hence, option A is correct

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

The mean free path of a molecule of He gas is $\alpha $. Its mean free path along any arbitrary coordinate axis will be

  1. $\alpha $
  2. $\dfrac { \alpha }{ 3 } $
  3. $\dfrac { \alpha }{ \sqrt { 3 } } $
  4. $3\alpha $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The mean free path in 3D is lambda = 1 / (sqrt(2) * pi * n * d^2). When considering motion along a single coordinate axis, the effective mean free path is reduced by a factor of sqrt(3) due to the projection of the velocity components.

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

The mean free path and rms velocity of a nitrogen molecule at a temperature 17C are $1.2 \times 10^{-7}$ m and $5 \times 10^2$ m/s respectively.The time between two successive collisions

  1. $2.4 \times 10^{-10}$ S
  2. $1.2 \times 10^{-10}$ S
  3. $3.4 \times 10^{-13}$ S
  4. $3.4 \times 10^{-10}$ S
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mean free path $\lambda=1.2 \times 10^{-7}$

rms velocity  $V _{rms}=5\times 10^{2} m/s$
Time betweem succesive collisions:
$T=\dfrac{\lambda}{V _{rms}}$
$=\dfrac{1.2 \times 10^{-7}}{5\times 10^2}$
$=0.24 \times 10^{-9}$
$=2.4 \times 10^{-10} s$

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

The mean free path of the molecules of a gas depends on 

  1. the diamter of molecules

  2. molecular density of gas

  3. both'a' and 'b'

  4. neither 'a' nor 'b'
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The mean free path formula lambda = 1 / (sqrt(2) * pi * n * d^2) shows that it depends on both the molecular diameter (d) and the molecular number density (n).

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

If the pressure in a closed vessle is reduced by drawing out some gas the mean-free path of molecules

  1. losing their kinetic energy

  2. sticking to the walls

  3. changing their momenta due to collision with the walls

  4. getting accelerated towards the wall
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since reduced pressure will result in the reduction of collision with the walls, average momentum will change and hence the mean free path.

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

State whether true or false:

Mean free path order for some gases at 273 K and 1 atm P is
$He > H _2 > O _2 > N _2 > CO _2$

  1. True

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

As atomicity of gas increases, its mean path decreases, also as attraction force between gas molecules increases, mean free path decreases so order is
$He > H _2 > O _2 > N _2 > CO _2$

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

Consider the following statements for air molecules in an air tight container.
(I) The average speed of molecules is larger than root mean square speed.
(II) Mean free path of molecules is larger than the mean distance between molecules.
(III) Mean free path of molecules increases with temperature.
(IV) The rms speed of nitrogen molecule is smaller than oxygen molecule. The true statements are.

  1. Only II

  2. II & III

  3. II & IV

  4. I, II & IV
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
(I)
$v _{avg} = \sqrt{\dfrac{8kT}{m\pi}}$
$v _{rms} = \sqrt{\dfrac{3kT}{m}}$
$ v _{avg}  \gt  v _{rms}$
so (I) is  correct.
(II)
The mean free path of a molecule is smaller  than the  distance between molecules.
( II ) is wrong.
(III) 
Mean free path is  directly prop to temp T.
$\lambda = \dfrac{RT}{\sqrt{2}\pi d^2 N _{A}P}$
so (III) is correct.
(IV)
$v _{rms} = \sqrt{\dfrac{3kT}{m}}$
Since  $ m _{N _2} < m _{O _2}$, rms speed of nitrogen is more than rms speed of oxygen molecule.
so (IV) is wrong.


Multiple choice chemistry combustion and flame structure of flame flame combustion

What is the maximum possible temperature( in $^0 C$) of a Bunsen burner flame? Assume that the gas is pure methane and that it is pre-mixed with sufficient air to permit complete combustion.

  1. 1500

  2. 4000

  3. 5000

  4. 1100
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The adiabatic flame temperature of a methane-air flame is approximately 1900-2000 degrees Celsius. Among the provided options, 1500 is the most reasonable estimate for a standard Bunsen burner flame, as heat losses prevent it from reaching the theoretical maximum.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

State whether true or false :
A gas thermometer measures temperature with the variation in pressure or volume of a gas.

  1. True

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

A gas thermometer measures temperature by the variation in volume or pressure of a gas.This thermometer functions by Charles's Law. Charles's Law states that when the temperature of a gas increases, so does the volume.

Using Charles's Law, the temperature can be measured by knowing the volume of gas at a certain temperature by using the formula, written below. Translating it to the correct levels of the device that is holding the gas. This works on the same principle as mercury thermometers.

${\displaystyle V\propto T\,},$
or

${\displaystyle {\dfrac {V}{T}}=k} $
T is the temperature.

V is the volume.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

The volume of gas is reduced to half from its original volume. The specific heat will be :

  1. reduce to half

  2. be doubled

  3. remain constant

  4. increase four times
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Specific heat capacity is an intensive property of a substance. It depends on the nature of the gas and the process (isobaric vs isochoric), not on the volume of the gas.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

Liquids are similar to gases because:

  1. both possess the property of flowing and take the volume of the containers

  2. both diffuse and take the shape of the containers

  3. both are readily compressible and diffuse

  4. both are capable of infinite expansion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Liquids and gases are similar in both shape and volume because they both have its' shape determined by its' surroundings. 

$\Longrightarrow $ Both diffuses and take the shape of containers.

Multiple choice chemistry materials around us and different types of houses materials around us matter and its states different states of matter

Gases do not have a definite shape because:

  1. molecules exert no force of attraction or repulsion upon one another

  2. molecules exert force of attraction

  3. molecules exert force repulsion upon one another

  4. both b and c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The molecules exert no force of attraction or repulsion upon one another. I.e., the molecules are independent of each other. This is the reason gases do not have a definite shape.

Multiple choice chemistry materials around us and different types of houses materials around us matter and its states different states of matter

The property of compressibility is :

  1. maximum in solids

  2. least in solids

  3. maximum in liquids

  4. least in gases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Solids are held in fixed positions, they can only vibrate. Because the particles can not move, solids have a definite shape and volume, and can't flow. Because the particles are already packed closely together, solids can't easily be compressed.