Kinetic Theory of Gases PYQs Set 5 (PDF)

Set 5 of 8 · Questions 121-150 of 212

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Mere Teacher · Previous Year Questions NEET Physics · Kinetic Theory of Gases · Set 5 (Q121-150)
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121. $A body is said to be opaque to the radiation if (a, r and t are coefficient of absorption, reflection and transmission respectively)$ (1) $t = 0 and a + r = 1$ (2) $a = r = t$ (3) $t \neq = 0$ (4) $a = 0, r = 1, t = 1$ 122. $Consider 1 cc sample of air at absolute temperature T_{0} at sea level and another 1 cc sample of air at a height where pressure is one-third atmosphere. The absolute temperature T of the sample at the height is -$ (1) $Equal to (T_{0} /3)$ (2) $Equal to (3/ T_{0})$ (3) $Equal to T_{0}$ (4) $Cannot be determined in terms of T_{0} from the above data$ 123. $The molar specific heat of an ideal gas at constant pressure and constant volume is ' C_{P}' and ' C_{Y}' respectively. If ' R' is the universal gas constant and the ratio of ' C_{p}' to ' C_{Y}' is ' γ' then ' C_{V}' is equal to$ (1) $\frac{1 - γ}{1 + γ}$ (2) $\frac{1 + γ}{1 - γ}$ (3) $\frac{γ - 1}{R}$ (4) $\frac{R}{γ - 1}$ 124. $The molecules of a given mass of a gas have rms velocity of 200 ms^{- 1} at 27^{\circ} C and 1.0 \times 10^{5} Nm^{- 2} pressure. When the temperature and pressure of the gas are respectively, 127^{\circ} C and 0.05 \times 10^{5} Nm^{- 2}, the rms velocity of its molecules in ms^{- 1} is [NEET 2016]$ (1) $\frac{400}{3}$ (2) $\frac{100 2}{3}$ (3) $\frac{100}{3}$ (4) $1002$ 125. $Under which of the following conditions is the law PV = RT obeyed most closely by a real gas$ (1) $High pressure and high temperature$ (2) $Low pressure and low temperature$ (3) $Low pressure and high temperature$ (4) $High pressure and low temperature$ 126. $A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature T. Considering only translational and rotational modes, the total internal energy of the system is:$ (1) $15 RT$ (2) $12 RT$ (3) $4 RT$ (4) $20 RT$ 127. $N molecules each of mass m of gas A and 2 N molecules each of mass 2 m of gas B are contained in a vessel which is maintained at temperature T . The mean square velocity of the molecules of gas B is denoted by V_{2}^{2} and the mean square of the x -component velocity of the molecules of gas A is denoted by V_{1}^{2}, then \frac{V _{1}}{V _{2}} is$ (1) $2$ (2) $1$ (3) $\frac{2}{3}$ (4) $\frac{2}{3}$ 128. $A mixture of 2 moles of helium gas (atomic mass = 4u), and 1 mole of argon gas (atomic mass =40u) is kept at 300K in a container. The ratio of their rms speeds (\frac{V _{rms} ( helium )}{V _{rms} ( argon )}), is close to:$ (1) $3.16$ (2) $0.32$ (3) $0.45$ (4) $2.24$ 129. $The average kinetic energy of a molecule of the gas is$ (1) $proportional to absolute temperature$ (2) $proportional to volume$ (3) $proportional to pressure$ (4) $dependent on the nature of the gas$ 130. $Assuming the nitrogen molecule is moving with r . m . s . velocity at 400 K the de-Broglie wavelength of nitrogen molecule is close to (Given : nitrogen molecule weight: 4.64 \times 10^{- 26} kg, Boltzman constant 1.38 \times 10^{- 23} J / K, Planck constant : : 6.63 \times 10^{- 34} J . s)$ (1) $0.24 Å^{\circ}$ (2) $0.20 Å^{\circ}$ (3) $0.34 Å^{\circ}$ (4) $0.44 Å^{\circ}$ 131. $In the expression for Boyle's law, the product ' PV' has dimensions of$ (1) $force$ (2) $impulse$ (3) $energy$ (4) $momentum$ 132. $The volume V of an enclosure contains amixture of three gases, 16 g of oxygen, 28 g of nitrogen and 44 g of carbon dioxide at absolute temperature T .Consider R as universal gas constant. The pressure of the mixture ofgases is :$ (1) $\frac{88 RT}{V}$ (2) $\frac{3 RT}{V}$ (3) $\frac{5}{2} \frac{RT}{V}$ (4) $\frac{4 RT}{V}$ 133. $At constant temperature, increasing the pressure of a gas by 5 % its volume will decrease by$ (1) $5 %$ (2) $5.26 %$ (3) $4.20 %$ (4) $4.70 %$ 134. $The number of rotational degrees of freedom of a monatomic molecule is$ (1) $2$ (2) $1$ (3) $0$ (4) $3$ 135. $For a molecule of an ideal gas, the number density is 22 \times 10^{8} cm^{- 3} and the mean free path is \frac{10 ^{- 2}}{π} cm . The diameter of the gas molecule is$ (1) $5 \times 10^{- 4} cm$ (2) $0.5\times 1 0^{- 4} cm$ (3) $2.5\times 1 0^{- 4} cm$ (4) $4 \times 10^{- 4} cm$ 136. $Heat energy is incident on the surface at the rate of 1000 J / min . If coefficient of absorption is 0.8 and coefficient of reflection is 0.1 , then heat energy transmitted by the surface in 5 minutes is$ (1) $100 J$ (2) $500 J$ (3) $700 J$ (4) $900 J$ 137. $On the basis of kinetic theory of gases, the gas exerts pressure because its molecules:$ (1) $suffer change in momentum when impinge on the walls of container.$ (2) $continuously stick to the walls of container.$ (3) $continuously lose their energy till it reaches wall.$ (4) $are attracted by the walls of container.$ 138. $The pressure of a gas is proportional to$ (1) $the sum of kinetic and potential energies$ (2) $potential energy$ (3) $kinetic energy$ (4) $None of the above$ 139. $In non-rigid diatomic molecule with an additional vibrational mode$ (1) $81 C_{v}^{2} = 49 C_{P}^{2}$ (2) $49 C_{v}^{2} = 25 C_{P}^{2}$ (3) $49 C_{V}^{2} = 81 C_{P}^{2}$ (4) $25 C_{v}^{2} = 49 C_{P}^{2}$ 140. $If one mole of the polyatomic gas is having twovibrational modes and β is the ratio of molarspecific heats for polyatomic gas (β = \frac{C _{P}}{C _{v}}) thenthe value of β is :$ (1) $1.02$ (2) $1.2$ (3) $1.25$ (4) $1.35$ 141. $A mixture of one mole of monoatomic gas and one mole of a diatomic gas (rigid) are kept at room temperature (27^{\circ} C) . The ratio of specific heat of gases at constant volume respectively is:$ (1) $\frac{7}{5}$ (2) $\frac{3}{5}$ (3) $\frac{5}{3}$ (4) $\frac{3}{2}$ 142. $An ideal gas equation can be written as p = \frac{ρRT}{M _{0}} where, ρ and M_{0} are respectively, [NEET 2020]$ (1) $mass density, mass of the gas$ (2) $number density, molar mass$ (3) $mass density, molar mass$ (4) $number density, mass of the gas$ 143. $The energy (in eV) possessed by a neon atom at 77^{\circ} C is (Blotzmann constant, K_{B} = 1.38 \times 10^{- 23} J K^{- 1})$ (1) $1.32 \times 10^{- 3}$ (2) $3.20 \times 10^{- 4}$ (3) $4.52 \times 10^{- 2}$ (4) $3.88 \times 10^{- 2}$ 144. $The volume occupied by the molecules contained in 4.5 kg water at STP, if the intermolecular forces vanish away is [NEET 2022]$ (1) $5.6 \times 10^{3} m^{3}$ (2) $5.6 \times 10^{- 3} m^{3}$ (3) $5.6 m^{3}$ (4) $5.6 \times 10^{6} m^{3}$ 145. $Calculate the value of mean free path (λ) for oxygen molecules at temperature 27^{\circ} C and pressure 1.01 \times 10^{5} Pa . Assume the molecular diameter 0.3 nm and the gas is ideal.$ (1) $58 nm$ (2) $32 nm$ (3) $86 nm$ (4) $102 nm$ 146. $Two moles of helium has is mixed gas is mixed with three moles of hydrogen molecules (taken to be rigid). What is the molar specific heat of mixture at constant volume ? (R=8.3J/mol K)$ (1) $19.7 J/mol K$ (2) $15.7 J/mol K$ (3) $17.4 J/mol K$ (4) $21.6 J/mol K$ 147. $The average thermal energy for a monoatomic gas is (where, k_{B} is Boltzmann constant and T is absolute temperature.) [NEET 2020]$ (1) $\frac{3}{2} k_{B} T$ (2) $\frac{5}{2} k_{B} T$ (3) $\frac{7}{2} k_{B} T$ (4) $\frac{1}{2} k_{B} T$ 148. $At what temperature an oxygen molecule has the same r.m.s velocity as the hydrogen molecule has at 20 K ?$ (1) $160 K$ (2) $320 K$ (3) $293 K$ (4) $347 K$ 149. $One mole of the ideal gas goes through the process p = p_{0} (1 - α (\frac{V}{V _{0}})^{3}), where p and V are pressure and volume, p_{0}, V_{0} and α are constants. If the maximum attainable temperature of the gas is (\frac{3}{4}) \frac{p _{0} V _{0}}{R}, then the value of α is$ (1) $2$ (2) $\frac{1}{2}$ (3) $\frac{1}{4}$ (4) $4$ 150. $A sample contains mixture of helium and oxygen gas. The ratio of root mean square speed of helium and oxygen in the sample, is:$ (1) $\frac{1}{32}$ (2) $\frac{2 2}{1}$ (3) $\frac{1}{2 2}$ (4) $\frac{1}{4}$