Previous year questions with solutions · 2000 – 2026
| Year | Questions | Papers | Avg / paper | Weightage |
|---|---|---|---|---|
| 2026 | 3 | 2 | 1.5 | 3.33% ▼ 25% vs last year |
| 2025 | 2 | 1 | 2 | 4.44% ▲ 122.2% vs last year |
| 2024 | 2 | 2 | 1 | 2.00% same as last year |
| 2023 | 1 | 1 | 1 | 2.00% same as last year |
| 2022 | 2 | 2 | 1 | 2.00% same as last year |
| 2021 | 1 | 1 | 1 | 2.00% ▼ 70% vs last year |
| 2020 | 3 | 1 | 3 | 6.67% ▲ 200% vs last year |
| 2019 | 1 | 1 | 1 | 2.22% same as last year |
| 2018 | 1 | 1 | 1 | 2.22% same as last year |
| 2017 | 1 | 1 | 1 | 2.22% same as last year |
| 2016 | 2 | 2 | 1 | 2.22% ▼ 33.3% vs last year |
| 2015 | 3 | 2 | 1.5 | 3.33% ▲ 50% vs last year |
| 2014 | 1 | 1 | 1 | 2.22% ▼ 33.3% vs last year |
| 2013 | 3 | 2 | 1.5 | 3.33% ▲ 56.7% vs last year |
| 2008 | 1 | 1 | 1 | 2.13% ▼ 2.1% vs last year |
| 2004 | 1 | 1 | 1 | 2.17% ▼ 2.2% vs last year |
| 2000 | 1 | 1 | 1 | 2.22% |
A flask contains argon and chlorine in the ratio of 2 : 1 by mass. The temperature of the mixture is 27°C. The ratio of root mean square speed of the molecules of the two gases ( VArrmsVClrms ) is : (Atomic mass of argon = 40.0 u and molecular mass of chlorine = 70.0 u)
An ideal gas is made of polyatomic molecules. Each of the molecules has three translational, three rotational and f number of vibrational modes. If the ratio of heat capacities CP/CV of the gas is 8/7, then the value of f is:
The mean free path of molecules in an ideal gas A is half that of another ideal gas B. The diameter of the spherical molecules of gas A is twice the diameter of the molecules of B. If number densities of the gases A and B are nA and nB, respectively, the correct option is:
A container has two chambers of volumes V1 = 2 litres and V2 = 3 litres separated by a partition made of a thermal insulator. The chambers contain n1 = 5 and n2 = 4 moles of ideal gas at pressures p1 = 1 atm and p2 = 2 atm, respectively. When the partition is removed, the mixture attains an equilibrium pressure of
An oxygen cylinder of volume 30 litre has 18.20 moles of oxygen. After some oxygen is withdrawn from the cylinder, its gauge pressure drops to 11 atmospheric pressures at temperature 27 . The mass of the oxygen withdrawn from the cylinder is nearly equal to: [Given, R = 10012 J mol-1 K-1, and molecular mass of O2 = 32, 1 atm pressure = 1.01 105 N/m2]
The following graph represents the T-V curves of an ideal gas (where T is the temperature and V the volume) at three pressures P1, P2 and P3 compared with those of Charles's law represented as dotted lines. [figure] Then the correct relation is :
According to the law of equipartition of energy, the number of vibrational modes of a polyatomic gas of constant = CPCV is (CP and CV are the specific heat capacities of the gas at constant pressure and constant volume, respectively):
The temperature of a gas is -50 . To what temperature the gas should be heated so that the rms speed is increased by 3 times?
The volume occupied by the molecules contained in 4.5 kg water at STP, if the intermolecular forces vanish away is
Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains helium (monoatomic), the second contains fluorine (diatomic) and the third contains sulfur hexafluoride (polyatomic). The correct statement, among the following is :
The average thermal energy for a mono-atomic gas is : (kB is Boltzmann constant and T absolute temperature)
The mean free path for a gas, with molecular diameter d and number density n can be expressed as :
A cylinder contains hydrogen gas at pressure 249 kPa and temperature 27 . Its density is : (R = 8.3 J mol-1 K-1)
Increase in temperature of a gas filled in a container would lead to :
At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the Earth's atmosphere? (Given : Mass of oxygen molecule (m) = 2.76 10-26 kg, Boltzmann's constant kB = 1.38 10-23 J K-1)
A gas mixture consists of 2 moles of O2 and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is
The molecules of a given mass of a gas have r.m.s. velocity of 200 m s-1 at 27 and 1.0 105 N m-2 pressure. When the temperature and pressure of the gas are respectively, 127 and 0.05 105 N m-2, the r.m.s. velocity of its molecules in m s-1 is
A given sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T. The mass of each molecule of the gas is m. Which of the following gives the density of the gas ?
Two vessels separately contain two ideal gases A and B at the same temperature, the pressure of A being twice that of B. Under such conditions, the density of A is found to be 1.5 times the density of B. The ratio of molecular weight of A and B is
4.0 g of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0 J K-1 mol-1. If the speed of sound in this gas at NTP is 952 m s-1, then the heat capacity at constant pressure is (Take gas constant R = 8.3 J K-1 mol-1)
The ratio of the specific heats CpCv = in terms of degrees of freedom (n) is given by
The mean free path of molecules of a gas, (radius r) is inversely proportional to
In the given (V - T) diagram, what is the relation between pressure P1 and P2? [figure]
The amount of heat energy required to raise the temperature of 1 g of Helium at NTP, from T1 K to T2 K is
In a vessel, the gas is at pressure P. If the mass of all the molecules is halved and their speed is doubled, then the resultant pressure will be
At 10 the value of the density of a fixed mass of an ideal gas divided by its pressure is x. At 110 this ratio is
The equation of state for 5 g of oxygen at a pressure P and temperature T, when occupying a volume V, will be (where R is the gas constant)
To find out degrees of freedom, the expression is