Chemistry · Physics

Gases and Gas Laws

252 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

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 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
C Correct answer
Explanation

Density is calculated as mass divided by volume. The total mass of the nitrogen gas remains constant throughout the compression process. By finding the initial mass from the initial volume and density, and dividing it by the final volume of 3.92 ml, the resulting density is obtained.

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
Multiple choice chemistry quantitative chemistry molecular mass relative formula mass masses of atoms and molecules

How many grams of carbon dioxide is dissolved in 1 litre bottle of carbonated water if the manufacturer uses a pressure of 2.4 atmosphere in the bottling process at 25 degree Celsius?

  1. 1.52

  2. 4.2

  3. 3.1

  4. 3.52

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

According to Henry's Law, the solubility of a gas is proportional to its partial pressure. Using the standard solubility of CO2 in water at 25 degrees Celsius and 1 atm, one can scale the value to 2.4 atm.

Multiple choice chemistry quantitative chemistry molecular mass relative formula mass masses of atoms and molecules

Two flasks A and B of equal volumes are kept under similar conditions of temperature and pressure. If flask A holds 16.2 g of gas X while flask B holds 1.012 g of hydrogen, calculate the relative molecular mass of gas X:

  1. 20 g

  2. 32 g

  3. 28 g

  4. 44 g

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

A mole is equal to the relative molecular mass of a gas. As given, the number of moles of gas X and hydrogen are same in the two flasks.
Therefore no. of moles in 2g of hydrogen gas = 1
No. of moles in 1.01g of hydrogen gas = 1/2
Now the weight of gas X that contains 1/2 moles = 16.2g
Weight of gas X that contains 1mole = $\frac{16.2}{1/2}$ = 32g

Multiple choice chemistry quantitative chemistry molecular mass relative formula mass masses of atoms and molecules

The weight of $1$ litre of a glass at STP is $2$ grams, its molecular weight is:

  1. $44.4$
  2. $44.8$
  3. $44.1$
  4. $55.8$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$At\quad STP,\quad volume\quad of\quad 1\quad mole\quad gas\quad =\quad 22.4\quad L\ Mass\quad of\quad 1L\quad gas\quad =\quad 2g\ Mass\quad of\quad 22.4L\quad gas\quad =\quad 2\times 22.4\quad =\quad 44.8\ So,\quad molecular\quad weight\quad of\quad gas\quad =\quad 44.8\ So,\quad correct\quad answer\quad is\quad option\quad B.$

Multiple choice chemistry quantitative chemistry molecular mass relative formula mass masses of atoms and molecules

M g of a substance when vaporised occupy a volume of 5.6 litre at NTP. The molecular mass of the substance will be: 

  1. $M$
  2. $2M$
  3. $3M$
  4. $4M$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Given,
$Mg$ of substance occupy volume$=5.6\,litre $ at NTP.
At NTP,
1 mol occupy 22.4 litre of volume.
5.6 litre$=Mg$
22.4 litres$=4\,Mg$ of substance.
So, Molecular mass of gas$=4\,Mg/mol$
Multiple choice chemistry chemical equilibrium equilibrium in chemical processes introduction to equilibrium chemical equilibrium and acids-bases

Gaseous $ N _{2}O _{4} $ dissociates into gaseous $ NO _{2} $ according to the reaction $ N _{2}O _{4} (g) \rightleftharpoons 2NO _{2}(g)$ at 300 K and 1 atm pressure, the degree of dissociation of $ N _{2}O _{4} $ is 0.2. If one mole of $ N _{2}O _{4} $ gas is contained in a vessel, then the density of the equilibrium mixture is : 

  1. 3.11 g/L

  2. 4.56 g/L

  3. 1.56 g/L

  4. 6.22 g/L

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

$N _2O _4\longrightarrow 2NO _2$


at $t=0$, moles of $N _2O _4=1$, moles of $NO _2=0$

at $t=equilibrium$, mole of $N _2O _4=1-a$, mole of $NO _2=2a$

$a$=degree of dissociation.

Molecular weight of mixture$=\cfrac {(1-a)\times\text{molar mass of }N _2O _4+2a\times \text{molar mass of }NO _2}{(1-a+2a)}$
                                                $=\cfrac {(1-0.2)(28+64)+2\times 0.2\times (14+32)}{1+0.2}$
$M=76.66$

$P=1 atm,T=300K,$

$d=PM/RT$

    $=\cfrac {1\times 76.66}{0.082 \times 300}=3.11\  gm/lit\ $ .