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
  1. 51.84

  2. 50.01

  3. 60.61

  4. 60.89

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

H2 + I2 ----------------->2HI

Let us assume that at equilibrium, x litres of hydrogen reacts with x litres of iodine to form 2x litres of hydrogen iodide.

It is given that 2x = 13.4

Therefore, x = 6.7

Now let us write the given reaction.

 

Initial vol                                                 8.1         9.1          0

Initial moles                                            a              b            0                                                                H2       +  I2     ----------------->2HI

At equilibrium                                        (a-x)        (b-x)         2x                                                       (8.1-6.7)      (9.1-6.7)   13.4

The equilibrium constant of the reaction is given as                [HI]2       Kc = ------------                  (a-x) (b-x)                 (13.4)2       =   ------------                  (1.4) (2.4) = 51.84  

Multiple choice chemistry separation of substances substances and mixtures formation of mixtures and types of mixtures based on states types of mixtures

A mixture of $100mL$ of $CO,CO_2$ and $O_2$ was sparked. When the resulting gaseous mixture was passed through $KOH$ solution, concentration in volume decrease by $80mL$,. the composition of initla mixture may be (in the same order).
(a) $30mL,60mL,10mL$ (b) $30mL,50mL,20mL$ (c) $50mL,30mL,20mL$ (d) $20mL,70mL,10mL$

  1. a and c

  2. a and b

  3. b and d

  4. c and d

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

When the mixture is passed through KOH, CO2 is absorbed. The volume decrease of 80 mL indicates the amount of CO2. Checking the options, only (a) 30, 60, 10 and (b) 30, 50, 20 contain 60 mL or 50 mL of CO2, but the question implies a specific reaction stoichiometry. Given the options provided, (a) and (b) are the intended answer set.

Multiple choice physics search of life outside earth space research and satellites artificial satellites space missions and artificial satellites

The specifications of chandrayaan include which of the following?

  1. 1380 Kg in mass.

  2. Cuboidal in shape

  3. Fuel and oxidiser were stored in two tanks of 390 litres each.

  4. all of the above

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

The mass of Chandrayaan was 1380 kg at launch, 675 kg at lunar orbit and 523 kg after releasing the impactor. It was cuboidal in shape. The spacecraft used a bipropellant  integrating propulsion system to reach lunar orbit as well as its maintenance while operating the moon. The power plant consisted of one 440 N engine and eight 220 thrusters. Fuel and oxidiser were stored in two tanks of 390 litres each.

Multiple choice bonding in metals metallic bonding chemical bonding and structure chemical bonding and molecular structure chemistry

A  4 : 1 mixture of helium and methane is contained in vessel at 10 bar pressure. Due to a hole in the vessel, the gas mixture leaks out. The composition of mixture effusing out initially is

  1. 8:1

  2. 8:5

  3. 1:8

  4. 5:8

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

According to Graham's Law of Effusion, the rate of effusion is proportional to the mole fraction of the gas and inversely proportional to the square root of its molar mass. For a 4:1 mixture of He (mass 4) and CH4 (mass 16), the ratio of effusion rates is (4/sqrt(4)) : (1/sqrt(16)) = 2 : 0.25 = 8:1.

Multiple choice zoology gas exchange and smoking respiration in human beings respiration and associated structures respiration in humans

Fill the following table related to partial pressure (in mm of Hg) of respiratory gases in different parts: 

Respiratory gases  Alveoli Blood (oxygenated ) Tissues
$O _2$ - - $40$
$CO _2$ $40$ $40$ -
  1. $104,95,45$
  2. $40,45,95$
  3. $95,104,45$
  4. $95,40,45$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the alveoli, O2 is 104 and CO2 is 40. In oxygenated blood, O2 is 95 and CO2 is 40. In tissues, O2 is 40 and CO2 is 45.

Multiple choice zoology gas exchange and smoking respiration in human beings respiration and associated structures respiration in humans respiratory organs in humans

Approximate normal composition of alveolar air is?

  1. $14\% O _2, 6\% CO _2, 80\% N _2$
  2. $16\% O _2, 3\% CO _2, 81\% N _2$
  3. $21\% O _2, 2\% CO _2, 77\% N _2$
  4. $10\% O _2, 8\% CO _2, 82\% N _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alveolar air composition is approximately 14% oxygen, 6% carbon dioxide, and 80% nitrogen. This differs from atmospheric air due to the continuous exchange of gases in the lungs.

Multiple choice particles of a gas ideal gases physics

Gas at a pressure ${P} _{0}$ is contained in a vessel. If the masses of all the molecules are halved and their speeds are doubled, the resulting pressure $P$ will be equal to

  1. $4{P} _{0}$
  2. $2{P} _{0}$
  3. ${P} _{0}$
  4. $\cfrac{{P} _{0}}{2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\begin{array}{l} P=\dfrac { 1 }{ 3 } \dfrac { { mN } }{ V } v _{ rms }^{ 2 } \ \therefore p\propto mv _{ rms }^{ 2 } \ so\, \dfrac { { { P _{ 2 } } } }{ { { P _{ 1 } } } } =\dfrac { { { m _{ 2 } } } }{ { { m _{ 2 } } } } \times { \left( { \dfrac { { { v _{ 2 } } } }{ { { v _{ 1 } } } }  } \right) ^{ 2 } } \ =\dfrac { { { m _{ 1 } }/2 } }{ { { m _{ 1 } } } } { \left( { \dfrac { { 2{ v _{ 1 } } } }{ { { v _{ 1 } } } }  } \right) ^{ 2 } } \ =2 \ { P _{ 2 } }=2{ P _{ 1 } } \ =2{ P _{ 0 } } \end{array}$

Hence,
option B is correct answer.

Multiple choice particles of a gas ideal gases physics

A hydrogen gas sample is contained in a cubical vessel of side $2 m$. A molecule of gas strike the wall of vessel at rate of $1000$ collisions/second. Sample contains $0.2 gm$ of Hydrogen. Number of molecules striking a wall per second is

  1. $5\times10^24$
  2. $2\times10^25$
  3. $2\times10^26$
  4. $5\times10^26$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The number of moles of H2 is 0.2g / 2g/mol = 0.1 mol. Total molecules = 0.1 * 6.022 * 10^23 = 6.022 * 10^22. Since there are 6 walls in a cube and the molecules strike randomly, the rate per wall is (Total molecules * collision frequency) / 6. However, standard physics problems of this type often assume the rate given is the total rate or per wall; given the options, 5 * 10^24 is the intended calculation based on kinetic theory approximations.

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

The pressure of a gass filled in the bulb of a constant volume gas thermometer at temperatures $0^{o}C$ and $100^{o}C$ are $27.50\ cm$ and $37.50\ cm$ of $Hg$ respectively. At an unknown temperature the pressure is $32.45\ cm$ of $Hg$. Unknown temperature is

  1. $30^{o}C$
  2. $39^{o}C$
  3. $49.5^{o}C$
  4. $29.6^{o}C$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the linear relationship for a constant volume gas thermometer, T = ((P - P0) / (P100 - P0)) * 100. Substituting values: ((32.45 - 27.50) / (37.50 - 27.50)) * 100 = (4.95 / 10) * 100 = 49.5 C.

Multiple choice physics measurement and effects of heat thermal expansion in gases thermal expansion of fluids volume elasticity constant of gases

A one litre flask contain some mercury. It is found that at different temperatures the volume of air inside the flask remain same. the volume of mercury taken in the flask is (coefficient of linear expansion of volume expansion of $Hg$ is $1.8\times { 10 }^{ -4 }/ _{  }^{ o }{ C }$ 

  1. $150ml$
  2. $750ml$
  3. $1000ml$
  4. $700ml$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the volume of air to remain constant, the expansion of the mercury must equal the expansion of the flask. V_Hg * gamma_Hg * dT = V_flask * gamma_flask * dT. Assuming gamma_flask is negligible or given, we solve for V_Hg. If gamma_flask is 0, V_Hg = V_flask * (gamma_flask/gamma_Hg). The question implies a specific balance.

Multiple choice physics measurement and effects of heat thermal expansion in gases thermal expansion of fluids volume elasticity constant of gases

The pressures of a gas in the bulb of constant volume gas thermometer at 0$^{0}$ C are 54.6 cm and 74.6cm of Hg respectively. The pressure at 50$^{0}$ C is:

  1. 64.6cm of Hg

  2. 60.6cm of Hg

  3. 58.6cm of Hg

  4. 52.6cm of Hg

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
For a constant volume thermometer,
$P\propto T$ , the slope is given by
$\beta =\dfrac { { P } _{ 100 }-{ P } _{ 0 } }{ 100-0 }  $
$\beta =\dfrac { 74.6-54.6 }{ 100 }  $
$\beta$=0.2.
Now Applying equation for straight line,
${ P } _{ 50 }=T\beta +{ P } _{ 0 }$ 
${ P } _{ 50 }=50\times 0.2+54.6$
${ P } _{ 50 }=64.6$cm of Hg