Chemistry · Physics

Gases and Gas Laws

298 Questions

The study of gases and gas laws involves understanding the relationships between pressure, volume, and temperature of gases. This topic is essential for chemistry and physics sections in many competitive exams. Practice these questions to master concepts like the ideal gas law, partial pressure, and molecular properties.

Ideal gas law calculationsGas volume and pressureStoichiometry of gasesDensity of gasesBoltzmann constant applicationsThermal speed of sound

Gases 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

A container is divided into two equal parts I and II by a partition with a small hole of diameter d. The two partitions are filled with same ideal gas, but held at temperatures $T _I=150$K and $T _{II}=300$K by connecting to heat reservoirs. Let $\lambda _I$ and $\lambda _{II}$ be the mean free paths of the gas particles in the two parts such that $d > > \lambda _I$ and $d > > \lambda _{II}$. Then $\lambda _I/\lambda _{II}$ is close to.

  1. $0.25$
  2. $0.5$
  3. $0.7$
  4. $1.0$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given,

Partition has hole of diameter $d$, Mean pressure between both sections is equal.

Boltzmann constant ${{K} _{B}}$

At constant pressure, Mean Free path $\lambda \ \alpha \ \sqrt{{{K} _{B}}T}$

Mean free path in ${{1}^{st}}$ section ${{\lambda } _{I}}=\sqrt{{{K} _{B}}\times 150}$

Mean free path in ${{2}^{nd}}$ section ${{\lambda } _{II}}=\sqrt{{{K} _{B}}\times 300}$

$\dfrac{{{\lambda } _{I}}}{{{\lambda } _{II}}}=\dfrac{\sqrt{{{K} _{B}}\times 150}}{\sqrt{{{K} _{B}}\times 300}}=0.707$

Hence, $\dfrac{{{\lambda } _{I}}}{{{\lambda } _{II}}}\cong 0.7$ 

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

Calculate the means free path of nitrogen molecule at $27^o$C when pressure is $1.0$ atm. Given, diameter of nitrogen molecule $=1.5\overset{o}{A}$, $k _B=1.38\times 10^{-23}$J $K^{-1}$. If the average speed of nitrogen molecule is $675$ $ms^{-1}$. The time taken by the molecule between two successive collisions is?

  1. $0.6$ns
  2. $0.4$ns
  3. $0.8$ns
  4. $0.3$ns
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Here, $T=27^oC=27+273=300$K.
$P=1$atm $=1.01\times 10^5$N $m^{-2}$, d$=1.5\overset{o}{A}=1.5\times 10^{-10}$m,
$k _B=1.38\times 10^{-23}$J $K^{-1}, \lambda =?$
From $\lambda =\dfrac{k _BT}{\sqrt{2}\pi d^2p}=\dfrac{1.38\times 10^{-23}\times 300}{1.414\times 3.14(1.5\times 10^{-10})^2\times 1.01\times 10^5}$
$=4.1\times 10^{-7}$m
Time interval between two successive collisions
$t=\dfrac{distance}{speed}=\dfrac{\lambda}{v} = \dfrac{4.1\times 10^{-7}}{675}=0.6\times 10^{-9}s$
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

Estimate the mean free path for a water molecule in water vapor at $373K$,the diameter of the molecule is $2\ \times 10^{-10}\ m$ and at $STP$ number of molecular per unit volume is $2.7\ \times 10^{25}\ m^{-3}$ :

  1. $2.81 \times 10^{-7}\ m$
  2. $3 \times 10^{-7}\ m$
  3. $4 \times 10^{-7}\ m$
  4. $5 \times 10^{-7}\ m$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using the formula lambda = 1 / (sqrt(2) * pi * n * d^2) with n = 2.7 * 10^25 m^-3 and d = 2 * 10^-10 m, the result is approximately 2.81 * 10^-7 m.

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

There are two vessels of same consisting same no of moles of two different gases at same temperature . One of the gas is $CH _{4}$ & the other is unknown X. Assuming that all the molecules of X are under random motion whereas in $CH _{4}$ except one all are stationary. Calculate $Z _{1}$ for X in terms of $Z _{1}$ of $CH _{4}$. Given that the collision diameter for both gases are same & $\displaystyle (U _{rms}) _{x}=\frac{1}{\sqrt{6}}(Uav) _{CH _{4}}$.

  1. $\displaystyle \frac{2\sqrt{2}}{3\sqrt{\pi }}Z _{1}$
  2. $\displaystyle \frac{3\sqrt{2}}{2\sqrt{\pi }}Z _{1}$
  3. $\displaystyle \frac{2\sqrt{3}}{2\sqrt{\pi }}Z _{1}$
  4. $\displaystyle \frac{4\sqrt{2}}{3\sqrt{\pi }}Z _{1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

V, n, T $\rightarrow  same$(25) so $P\rightarrow $ also same ( P  5  25)
$\displaystyle \sigma \rightarrow same (25)$
given

$\displaystyle (v {rms})\times

x=\dfrac{1}{\sqrt{6}}(v _{avg.}) _{CH _{4}}$ &

$v _{rms}=\sqrt{\dfrac{3\pi }{8}}(v _{avg.})$ so
$\displaystyle \sqrt{\dfrac{3\pi }{8}}(v _{avg.}) _{CH _{4}}$
$\displaystyle \dfrac{(v _{avg.})x}{(v _{avg.}) _CH _{4}}=\sqrt{\dfrac{8}{3\pi }}.\frac{1}{\sqrt{6}}=\dfrac{2}{3\sqrt{\pi }}$
For X (9< ) : $\displaystyle Z _{1}=\sqrt{2}\pi \sigma ^{2}(v _{avg.}) _{x}N^{\ast }$
For CH
{4} (9< ) : $\displaystyle Z _{1}=\pi \sigma ^{2}(v _{avg.}) _{CH _{4}}N^{\ast }$
Since T, P, v, n are same, $N\ast $ will also be same.
$\displaystyle



\frac{Z _{1}X}{Z _{1}(CH _{4})}=\sqrt{2}\frac{(v _{avg.}) _{x}}{(v _{avg.}) _{CH _{4}}}=\sqrt{2}.\frac{2}{3\sqrt{\pi

}}$
$\displaystyle Z _{1}(X)=Z _{1}(CH _{4}).\frac{2\sqrt{2}}{3\sqrt{\pi }}$

Multiple choice physics energy transformations and energy transfers law of conservation of energy the law of conservation of energy types of energy

A domestic gas cylinder contains about 14.2 kg of LPG. A strong smelling substance called ethyl mercaptan is added to the LPG to detect the leakage of gas from the cylinder. On being lighted, it burs with a blue flame. One gram of LPG produces about 50 kJ of heat. Weight of the domestic cylinder is -

  1. 142 N

  2. 152 N

  3. 132 N

  4. 122 N

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Weight is calculated as mass times gravity (W = mg). Using g = 10 m/s^2, 14.2 kg * 10 m/s^2 = 142 N.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

A vessel contains a mixture of $7g$ of nitrogen and $8g$ of oxygen at temperature $T=300K$. If the pressure of the mixture is $1atm$, its density is 
$\left[ R=\cfrac { 25 }{ 3 } J/mol\quad K \right] $

  1. $0.6kg/{m}^{3}$
  2. $1.2kg/{m}^{3}$
  3. $1.5kg/{m}^{3}$
  4. $2kg/{m}^{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Molar mass of mixture $=\cfrac{total mass}{total mole}$

$M=\cfrac{15}{\cfrac{4}{14}+\cfrac{8}{16}}=15\M=15\ PM=\rho RT\ \rho=\cfrac{1(15)\times10^{-3}}{(\cfrac{25}{3}300)}\ \rho=\cfrac{15}{25}=\cfrac{3}{5}=0.6kg/m^3$

Multiple choice physics oscillations and waves standing waves in strings standing waves reflection of waves

A pipe of length $l _1$ closed at one end is kept in a chamber of gas density $1$. A second pipe open at both ends is placed in the second chamber of gas density $2$. The compressibility of both the gases is equal.Calculate the length of the second pipe if the frequency of the first overtone in both the cases is equal.

  1. $\displaystyle \dfrac{4}{3}l _{1}\sqrt{\dfrac{\mathrm{p} _{2}}{\mathrm{p} _{1}}}$
  2. $\displaystyle \dfrac{4}{3}l _{1}\sqrt{\dfrac{\mathrm{p} _{1}}{\mathrm{p} _{2}}}$
  3. $l _{1}\sqrt{\dfrac{\mathrm{p} _{2}}{\mathrm{p} _{1}}}$
  4. $l _{1}\sqrt{\dfrac{\mathrm{p} _{1}}{\mathrm{p} _{2}}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$l _{1}=\displaystyle \dfrac{3}{4}\dfrac{\mathrm{v} _{1}}{\mathrm{f} _{1}}$ , $l _{2}=\displaystyle \dfrac{\mathrm{v} _{2}}{\mathrm{f} _{2}}$

$\dfrac{3\mathrm{v} _{1}}{4l _{1}}=\dfrac{\mathrm{v} _{2}}{l _{2}}$

$l _{2}=\displaystyle \dfrac{4l _{1}\mathrm{v} _{2}}{3\mathrm{v} _{1}}=\dfrac{4l _{1}}{3}\sqrt{\dfrac{\mathrm{p} _{1}}{\mathrm{p} _{2}}}$

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

 The weight is required to get 2.24 litre of oxygen at STP is :

  1. 3.4 grams

  2. 34 grams

  3. 6.8 grams

  4. 68 grams

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

At STP, 1 mole of any gas occupies 22.4 liters. 2.24 liters of O2 is 0.1 moles. The molar mass of O2 is 32 g/mol. Mass = 0.1 moles * 32 g/mol = 3.2 grams. The closest option is 3.4 grams, likely due to a typo in the question or options.

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

26cc of $CO _2$ are passsed over red hot coke .The volume of CO evolved is :


 ${C _{\left( s \right)}} + C{O _{2\left( g \right)}} \to 2C{O _{\left( g \right)}}$ 

  1. 15cc

  2. 10cc

  3. 52cc

  4. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The reaction is C(s) + CO2(g) -> 2CO(g). According to the stoichiometry, 1 volume of CO2 produces 2 volumes of CO. Therefore, 26cc of CO2 will produce 26 * 2 = 52cc of CO.

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

At $0^o$C the density of nitrogen at $1$ atm is $1.25$ kg$/m^3$. The nitrogen which occupied $1500$ml at $0^o$C and $1$ atm was compressed at $0^o$C and $575$ atm and the gas volume was observed to be $3.92$ ml, in violation of Boyle's law. What was the final density of this non-ideal gas?

  1. $278$ $kg/m^3$
  2. $378$ $kg/m^3$
  3. $478$ $kg/m^3$
  4. $578$ $kg/m^3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice chemistry materials around us and different types of houses materials around us matter and its states different states of matter

In an evacuated rigid vessel of volume V liter, one mole of solid ammonium carbonate, $ NH _2CONH _4 $ , is taken and the vessel is hated to T K. The equilibrium total pressure of gases is found to be P atm. The percentage dissociation of solid into $ NH _3(g) $ and $ CO _2 (g) $ is 

  1. $ \dfrac { 100RT }{ 3PV } %$
  2. $ \dfrac { RT }{ 3PV } %$
  3. $ \dfrac { 100RT }{ PV } %$
  4. $ \dfrac { 300RT }{ PV } %$
Reveal answer Fill a bubble to check yourself
A Correct answer