Gas laws from KTG

Q.

At $363\mathrm{K}$, the vapour pressure of $\mathrm{A}$ is $21\mathrm{kPa}$ and that $\mathrm{B}$ is $18\mathrm{kPa}$ . One mole of $\mathrm{A}$ and $2$ moles of $\mathrm{B}$ are mixed. Assuming that solution is ideal, the vapour pressure of the mixture is ___________ $\mathrm{kPa}$. (Round off to the nearest integer).

Q.

The degree of freedom for monoatomic gas is:

1. 3

2. 6

3. 5

4. 2

Q. You are given sample of $1{\text{cm}}^3$ of $H_2$, $1{\text{cm}}^3$ of $O_2$ and $1{\text{cm}}^3$ of $C{l}_2$ which are at STP. The sample which has maximum number of molecules is

1. $H_2$
2. $O_2$
3. $C{l}_2$
4. All have same value

Q. Estimate the fraction of molecular volume to the actual volume occupied by oxygenm gas at STP. Take the diameter of an oxygen molecule to be 3 Å.

Q. an ideal gas has adiabatic exponent γ it contracts according to the law pv=α, where α is a positive cons†an t. for this process, the bulk modulus of the gas is 1)p 2)p/α 3)α p 4) (1-α)

Q.

A square wire frame of side 'L' is dipped in a liquid. On taking it out a membrane is formed. If the surface tension of liquid is T, the force acting on the liquid surface will be?

1. 10 TL

2. 2 TL

3. 8 TL

4. 4 TL

Q. Density ratio of $O_2$ and $H_2$ is $16:1$. The ratio of their rate of effusion under same conditions is

1. $4:1$
2. $1:4$
3. $1:2$
4. $2:1$

Q.

An adiabatic process is one in which_____

Q. Estimate the total number of air molecules (inclusive of oxygen, nitrogen, water vapour and other constituents) in a room of capacity 25.0 m3 at a temperature of 27 °C and 1 atm pressure.

Q.

If $p$: It is snowing, $q$: I am cold, then the compound statement $"$It is snowing and it is not that I am cold$$ is given by

1. $p\wedge \left(~q\right)$

2. $p\wedge q$

3. $\left(~p\right)\wedge q$

4. $\left(~p\right)\wedge \left(~q\right)$

5. $p\vee \left(~q\right)$

Q.

Three balloons are filled with different amounts of an ideal gas. One balloon is filled with 3 moles of the gas, filling the balloon to 30 L. The second balloon contains 2 moles of gas.

The third balloon occupies a volume of 45 L.

(i) What volume will the second balloon occupy?

(ii) How many moles of the gas does the third balloon contain?

1. 30 L; 4 moles

2. 20 L; 4.5 moles

3. 10L; 2 moles

4. 40L; 1.5 moles

Q.

The volume of a gas at ${200}^{\circ }C$ is 200 ml. If the temperature is reduced to $-{20}^{\circ }C$ at constant pressure, its volume will be

1. 17.26 ml

2. 192.7 ml

3. 19.27 ml

4. 172.6 ml

Q. An air bubble of volume 1.0 cm³ rises from the bottom of a lake 40 m deep at a temperature of 12 °C. To what volume does it grow when it reaches the surface, which is at a temperature of 35 °C ?

Q. Which one of the following graphs represents the behaviour of an ideal gas of given mass at constant pressure?

1. 
2. 
3. 
4. All of these

Q.

Boyle's law holds for an ideal gas during

1. Isobaric changes

2. Isothermal changes

3. Isochoric changes

4. Isotonic changes

Q. Given below are densities of some solids and liquids. Give rough estimates of the size of their atoms : [Hint : Assume the atoms to be ‘tightly packed’ in a solid or liquid phase, and use the known value of Avogadro’s number. You should, however, not take the actual numbers you obtain for various atomic sizes too literally. Because of the crudeness of the tight packing approximation, the results only indicate that atomic sizes are in the range of a few Å] Substance Atomic Mass (u) Density (103 Kg m-3) Carbon (diamond) 12.01 2.22 Gold 197.00 19.32 Nitrogen (liquid) 14.01 1.00 Lithium 6.94 0.53 Fluorine (liquid) 19.00 1.14

Q.

The gas which obeys Boyle's law for maximum range of temperature is

1. $C{O}_2$

2. $O_3$

3. $H_2$

4. He

Q. A metre long narrow bore held horizontally (and closed at one end) contains a 76 cm long mercury thread, which traps a 15 cm column of air. What happens if the tube is held vertically with the open end at the bottom ?

Q.

A sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T, the mass of each molecule is m. The expression for the density of gas is (k = Boltzmann constant)

1. 

2. 

3. 

4. mkT

Q. Which one of the following graph represents the behaviour of a ideal gas? Assume pressure is constant.

1. 
2. 
3. 
4. 

Q. An air bubble of volume $V_0$ is released by a fish at a depth $h$ in a lake. The bubble rises to the surface. Assume constant temperature and standard atmospheric pressure $P$ above the lake. The volume of the bubble just before touching the surface will be (density of water is $\rho )$
$($Assume that the radius of bubble is neglegible$)$

1. $V_0$
2. $V_0\left(\frac{\rho gh}{P}\right)$
3. $\frac{V_0}{(1+\frac{\rho gh}{P})}$
4. $V_0(1+\frac{\rho gh}{P})$

Q. Volume of a given amount of gas at ${57}^{\circ }\text{C}$ is $425.8{\text{cm}}^3$. If the temperature is decreased to ${37}^{\circ }\text{C}$ at constant pressure, then the volume of the gas would be :

1. $400{\text{cm}}^3$
2. $220{\text{cm}}^3$
3. $880{\text{cm}}^3$
4. $12.20{\text{cm}}^3$

Q. A vessel of volume, V=5.0 litres contain 1.4 g of nitrogen at temperature, T=1800 k. Find the pressure of gas if 30% of its molecules are dissosciated into atoms at this temperature

Q. A closed hollow insulated cylinder is filled with gas at $0^{\circ }$C and also contains an insulated piston of negligible weight and negligible thickness at the middle point. The gas on one side of the piston is heated to ${100}^{\circ }$ C .If the piston moves 5cm the length of the hollow cylinder is

1. 13.65 cm
2. 27.3 cm
3. 38.6 cm
4. 64.6 cm

Q. 60% of given sample of oxygen gas when raised to a high temperature dissociates into atoms.Ratio of its initial heat capacity(at const. vol.) to the final heat capacity(at const. vol.) will be-1)8/7, 2)25/26, 3)10/7, 4)25/27

Q. A gas is kept in a rigid cubical container. If a load of $15\text{kg}$ is put on the top of the container, then the pressure of the gas will:
[assume temperature remains constant]

1. increase
2. decrease
3. remain constant
4. first increase then decrease

Q. the pressure and density of a diatomic gas γ=7/5 change adiabatically from P, d to P, d if d/d=32 then P/P SHOULD BE

Q. From a certain apparatus, the diffusion rate of hydrogen has an average value of 28.7 cm³ s¯¹. The diffusion of another gas under the same conditions is measured to have an average rate of 7.2 cm³ s¯¹. Identify the gas. [Hint : Use Graham’s law of diffusion: R₁/R₂ = ( M₂ /M₁ )1/2, where R₁, R₂ are diffusion rates of gases 1 and 2, and M₁ and M₂ their respective molecular masses. The law is a simple consequence of kinetic theory.]

Q. A closed vessel contains a mixture of one mole of oxygen $\left(O_2\right)$ and two moles of Nitrogen $\left(N_2\right)$ at $300\text{K}$. Find the ratio of partial pressure exerted by $O_2$ to the total pressure exerted by mixture on the wall of vessel?

1. $1:3$
2. $3:1$
3. $2:3$
4. $1:2$

Q. An ideal gas is kept inside a $4\text{L}$ container at a temperature of $300\text{K}$ and a pressure of $6\text{atmospheres}$. If the pressure is held constant while the volume of the gas is doubled, then find out the new temperature of the gas.

1. $1200\text{K}$
2. $600\text{K}$
3. $300\text{K}$
4. $150\text{K}$