Two containers A and B are partly filled with water and closed. The volume of A is twice that of B and it contains half the amount of water in B. If both are at the same temperature, the water vapour in the containers will have pressure in the ratio of [1988]
Vapour pressure does not depend on the amount of substance. It depends on the temperature alone.
At constant volume, temperature is increased then
As the temperature increases, the average velocity increases. So, the collisions are faster.
A polyatomic gas with n degrees of freedom has a mean energy per molecule given by [1989]
According to law of equipartition of energy, the energy per degree of freedom is For a polyatomic gas with n degrees of freedom, the mean energy per molecule =
For a certain gas the ratio of specific heats is given to be γ = 1.5. For this gas [1990]
According to kinetic theory of gases, at absolute zero temperature [1990]
The average kinetic energy of a gas molecular is directly eruptional to absolute temperature only; this implies that all molecular motion stops if the temperature is reduced to absolute zero.
One mole of an ideal monoatomic gas requires 207 J heat to raise the temperature by 10 K when heated at constant pressure. If the same gas is heated at constant volume to raise the temperature by the same 10 K, the heat required is [Given the gas constant R = 8.3 J/ mol. K] [1990]
We know that Q_{v} = nC_{v}ΔT and Q_{p }= nC_{p}ΔT
Given Qp = 207 J
Relation between pressure (P) and energy (E) of a gas is [1991]
Three containers of the same volume contain three different gases. The masses of the molecules are m_{1}, m_{2} and m_{3 }and the number of molecules in their respective containers are N_{1}, N_{2 }and N_{3}. The gas pressure in the containers are P_{1}, P_{2} and P_{3 }respectively. All the gases are now mixed and put in one of these containers.The pressure P of the mixture will be [1991]
According to Dalton’s law of partial pressures, we have P = P_{1} + P_{2} + P_{3}
The number of translational degrees of freedom for a diatomic gas is [1993]
Number of translational degrees of freedom are same for all types of gases.
The temperature of a gas is raised from 27°C to 927°C.The root mean square speed is [1994]
As temperature increases from 300 K to 1200 K that is four times, so, c_{rms} will be doubled.
The equation of state, corresponding to 8g of O_{2} is[1994]
8g of oxygen is equivalent to (1/4) mole.
If C_{s} be the velocity of sound in air and C be the r.m.s velocity, then [1994]
Velocity of sound
R.M.S. velocity of gas molecules =
At 0 K, which of the following properties of a gas will be zero? [1996]
At 0 K, molecular motion stops. Hence, kinetic energy of molecules becomes zero.
The degree of freedom of a molecule of a triatomic ga s is[1999]
No. of degree of freedom = 3 K – N where K is no. of atom and N is the number of relations between atoms. For triatomic gas, K = 3, N = ^{3}C_{2} = 3
No. of degree of freedom = 3 (3) – 3 = 6
The equation of state for 5 g of oxygen at a pressure P and temperature T, when occupying a volume V, will be [2004]
[∵ PV = nRT]
At 10° C the value of the density of a fixed mass of an ideal gas divided by its pressure is x. At 110°C this ratio is: [2008]
Let the mass of the gas be m.
At a fixed temperature and pressure, volume is fixed.
Density of the gas,
(By question)
In the given (V – T) diagram, what is the relation between pressure P_{1} and P_{2} ? [NEET 2013]
P_{1} > P_{2}
As V = constant ⇒ P ∝ T
Hence from V–T graph P_{1 }> P_{2}
The amount of heat energy required to raise the temperature of 1g of Helium at NTP, from T_{1}K to T_{2}K is [NEET 2013]
From first law of thermodynamics ΔQ = ΔU + ΔW
In a vessel, the gas is at a pressure P. If the mass of all the molecules is halved and their speed is doubled, then the resultant pressure will be [NEET Kar. 2013]
When mass is halved and speed is doubled then Resultant pressure,= 2 P.
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