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The Gas Laws MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 25, 2023 25:23 PM | #NEET

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  • Gas laws(I) is considered one of the most asked concept.

  • 19 Questions around this concept.

Solve by difficulty

An ideal gas goes through a reversible cycle a\rightarrow b\rightarrow c\rightarrow d  has the V - T diagram

shown below. Process d\rightarrow a\: and \: b\rightarrow c are adiabatic .

The corresponding P - V diagram for the process is (all figures are schematic and not drawn to scale) :

 

In the adjacent V-T diagram,  what is the relation between P1 and P2?

 

A glass tube scaled at both ends is 1 \mathrm{~m} long. It lies horizontally with the middle 10 \mathrm{~cm} containing \mathrm{Hg}. The two ends of the tube, eqaul in length, contain air at 27^{\circ} \mathrm{C} and pressure 76 \mathrm{~cm}$ of $\mathrm{Hg} . The temperature at one end is kept 0^{\circ} \mathrm{C}  and at the other end it 127^{\circ} \mathrm{C}. Neglect the change in length of \mathrm{Hg} column. Then the change in length on two sides is

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When one temperature of an open room which has volume 50 m^{3} increases from 27^{\circ}C to 37^{\circ}C due to sunlight atmospheric pressure inside the room is 1 KPa. If n_{1} and n_{2} are no. of molecules in the room before and after heating then final the difference of molecules.

Volume temperature gas at constant pressure for a monoatomic gas (V\: in\: m^3,\: T\: in\: ^0C) is - 

Concepts Covered - 3

Gas laws(I)

BOYLE'S LAW

Boyle’s law : It states that, for a given mass of an ideal gas at constant temperature, the volume of a gas is inversely proportional to its pressure.

                                                             \ \ \ \ \ \ \ V \propto \frac{1}{P} \quad \\ \\ \text { or, } \quad P.V=\text { constant }

                                                                  \Rightarrow P_{1} V_{1}=P_{2}V_{2}

We can also write the above equation as,

                                                              P V=P\left(\frac{m}{\rho}\right)=\text { constant } 

                                                So, \Rightarrow \quad \frac{P}{\rho}=\text { constant or } \frac{P_{1}}{\rho_{1}}=\frac{P_{2}}{\rho_{2}}

We can represent the Boyle's law through the various graph, which is shown as - 

                                                  

 

CHARLE'S LAW - 

Charle's law : It states that, if the pressure remaining constant, the volume of the given mass of a gas is directly proportional to its absolute temperature.

From the above statement we can conclude the following equations - 

                                                                              \boldsymbol{V\ \propto \ T}

 

                                                                        So,  \\ \frac{V}{T} = Constant \\ \\ \\ \frac{V_1}{T_1} = \frac{V_2}{T_2}

This equation can also be written in terms of density and temperature as - 

                                                      \\ {\text { } \frac{V}{T}=\frac{m}{\rho T}=\text { constant }\left(\text { As volume } V=\frac{m}{\rho}\right)} \\ \\ \\ {\text { or, } \quad \rho T=\text { constant } \\ \\ \mathbf{\Rightarrow \rho_{1} T_{1}=\rho_{2} T_{2}}}

 

We can represent the Charle's law through the various graph, which is shown as -

 

                         

 

 

 

Gas laws(II)

Gay-Lussac’s law  - 

Gay-Lussac’s law or pressure law : If the volume remains constant, then the pressure of a given mass of a gas is directly proportional to its absolute temperature.

So, We can conclude the above statement in the following equation - 

 

                                                  P \propto T \text { or } \frac{P}{T}=\text { constant } \Rightarrow \frac{P_{1}}{T_{1}}=\frac{P_{2}}{T_{2}}

The graphical representation of Gay-Lussac's law is - 

 

                                               

 

AVAGADRO'S LAW - 

Avogadro’s law : Equal volume of all the gases under similar conditions of temperature and pressure contain equal number of molecules. It implies that - 

                                                               N_1 = N_2
N = Number of molecules in a particular gas.

Gas laws(III)

GRAHAM’S LAW OF DIFFUSION 

Graham’s law of diffusion: It states that when any two gases at the same pressure and temperature are allowed to diffuse into each other, then the rate of diffusion of each gas is inversely proportional to the square root of the density of the gas.

So we can say that, 

                                                                 r \propto \frac{1}{\sqrt{\rho}} \propto \frac{1}{\sqrt{M}} 

                                                         Where, r = rate of diffusion of gas

                                                                    \rho = Density of the gas

                                                                    M = Molecular weight of the gas

Now, from the above equation we can write,

                                                                \frac{r_{1}}{r_{2}}=\sqrt{\frac{\rho_{2}}{\rho_{1}}}=\sqrt{\frac{M_{2}}{M_{1}}}

 

DALTON'S LAW OF PARTIAL PRESSURE -

Dalton’s law of partial pressure :It states that the total pressure exerted by a mixture of non-reacting gases occupying a vessel is equal to the sum of the individual pressures which each gases exert if it alone occupied the same volume at a given temperature.

Now, let us have a mixture of 'n' gases, so from the above statement we can conclude that - 

 

                                                     \text { For } n \text { gases } P=P_{1}+P_{2}+P_{3}+\ldots . . P_{n}

Here, P = Pressure exerted by the mixture of gases

          P1,P2. . . . . . Pn = Partial pressure of the component gases.

 

 

 

 

Study it with Videos

Gas laws(I)
Gas laws(II)
Gas laws(III)

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Books

Reference Books

Gas laws(I)

Physics Part II Textbook for Class XI

Page No. : 321

Line : 31

Gas laws(II)

Physics Part II Textbook for Class XI

Page No. : 319

Line : 44

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