# Kinetic Theory of Gases – Question Paper 01 1

 1 Average kinetic energy of molecules is (MHT-CET-2004) (a) Directly proportional to square root of temperature (b) Directly proportional to absolute temperature (c) Independent of absolute temperature (d) Inversely proportional to absolute temperature Answer: (b) 2 The specific heat of a gas in isothermal process is (a) Zero (b) Negative (c) Remains constant (d) Infinite Answer: (d) 3 Latent heat of ice is (MHT-CET 2006) (a) Less than external latent heat of fusion (b) Equal to external latent heat of fusion (c) More then external latent heat of fusion (d) Twice the external latent heat of fusion Answer: (c) 4 The r.m.s. velocity of the molecules in the sample of helium is 5/7th that of the molecules in the sample of hydrogen. If the temperature of the hydrogen sample is 0°C that of helium is (NCERT-80) (a) 0°C (b) 0°K (c) 273°C (d) 100°C Answer: (a) 5 Mean square velocity of five molecules of velocities 2 m/s, 3 m/s, 4 m/s, 5 m/s and 6 m/s is (MHT-CET-2006) (a) 10 m2/s2 (b) 18 m2/s2 (c) 20 m2/s2 (d) 15 m2/s2 Answer: (b) 6 The difference between the principal specific heats of nitrogen is 300 J/kg °K and ratio of the two specific heats is 1.4. Then the CP is (MHT-CET-1999) (a) 1050 J/kg °K (b) 650 J/kg °K (c) 750 J/kg °K (d) 150 J/kg °K Answer: (b) 7 CP and CV denote the molar specific heats of a gas at constant pressure and at constant volume respectively. If and CP – CV= R, then CV is equal to (a) (b) (c) (d) Answer: (a) 8 A gas is taken in a sealed container at 300 K. it is heated at constant volume to a temperature 600 K. the mean K.E. of its molecules is (NCERT-80) (a) Halved (b) Doubled (c) Tripled (d) Quadrupled Answer: (b) 9 R.m.s. velocity of a gas molecule of mass m at given temperature is proportional to (CBSE-90) (a) m0 (b) m (c) (d) Answer: (d) 10 The mean kinetic energy of one gram-mole of a perfect gas at absolute temperature T is (MHT-CET-1999) (a) (b) (c) (d) Answer: (d) 11 The specific heat of a substance at its boiling point or melting point (a) Is zero (b) Is infinity (c) Is negative (d) Lies between 0 and 1 Answer: (b) 12 Mean kinetic energy per gm. Molecule of a gas is given by (MHT-CET 99) (a) (b) kT (c) (d) Answer: (a) 13 If for a gas this gas is made up of molecules which are (CBSE-92) (a) Diatomic (b) Mixture of diatomic and polyatomic (c) Mono atomic (d) Polyatomic Answer: (c) 14 CP and CV are the principal specific heat of a gas. In terms of mechanical units, CP – CV is equal to (a) R (b) (c) (d) Answer: (c) 15 A sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T, the mass of each molecules is m. the expression for the density of gas is (k = Boltzmann constant) (EAMCET 88) (a) mkT (b) (c) (d) Answer: (d) 16 One mole of ideal gas required 207 J heat to rise 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 (R = 8/3 J/mole °K) (MHT-CET-2000) (a) 1987 J (b) 29 J (c) 215.3 J (d) 124 J Answer: (d) 17 The average translational K.E. of O2 molecules (Molecular weight =32) at a particular temperature is .035 eV. What is the average translational K.E. of N2 Molecules (Molecular weight = 28) at the same temperature? (a) 0.028 eV (b) 0.055 eV (c) 0.035 eV (d) 0.075 eV Answer: (c) 18 At constant volume temperature is increased then (C.B.S.E 93) (a) Collision on walls will be less (b) Collision frequency will be increases (c) Collision will be in straight line (d) Collision will not change Answer: (b) 19 The specific heat of a gas (a) Has only one value (b) Has two values CP and CV (c) Is proportional to the square root of its absolute temperature (d) Can have any value between 0 and infinity Answer: (d) 20 Two specific heats of a perfect gas are related by (C.P.M.T-73, 78, MP.P.M.T.-84) (a) CP – Cν = (b) CP – Cν = J (c) CP – Cν = RJ (d) Answer: (a) 21 Which one of the following quantities can be zero on a average for the molecules of an ideal gas in equilibrium? (a) Kinetic energy (b) Density (c) Momentum (d) Speed Answer: (c) 22 The r.m.s velocity of hydrogen gas molecules at N.T.P. is ν m/se. the gas is heated at constant volume till the pressure becomes 4 times. The final r.m.s. velocity is, (A.F.M.C. PUNE-96) (a) V/2 (b) ν (c) 2 ν (d) 4 ν Answer: (c) 23 At a certain temperature, hydrogen molecules have r.m.s. velocity of 3 km/s. what is the r.m.s velocity of the oxygen molecules at the same temperature? (a) 0.25 km/s (b) 0.5 km/s (c) 0.75 km/s (d) 6 km/s Answer: (c) 24 We have a jar ‘A’ filled with a gas characterized by parameter P, V and T. another jar ‘B’ filled with a gas with parameters 2P, and 2T, where symbols have their usual meanings. The ratio of the number of molecules of jar ‘A’ to those of jar ‘B’ is (a) 1: 1 (b) 1: 2 (c) 2: 1 (d) 4: 1 Answer: (d) 25 A unit mass of solid converted to liquid at its melting point. Heat is required for this process is (MHT-CET-2003) (a) Specific heat (b) Latent heat of vaporization (c) Latent heat of fusion (d) External latent heat Answer: (c)