One mole of a diatomic ideal gas (y = 1.4) is taken through a cyclic process starting from point A. The process A→B is an adiabatic compression. B→C is isobaric expansion, C→D an adiabatic expansion and D→A is isochoric. The volume ratios are VA/VB = 16 and VC/VD = 2 and the temperature at A is TA = 300 K. 
1. Calculate the temperature of the gas at the point B and D
2. Find the efficiency of the cycle. 
3. The average translational kinetic energy of O2 (molar mass 32) molecules at a particular temperature is 0.048 eV. The translational kinetic energy of N2 (molar mass 28) molecules in eV at the same temperature is: 
(A) 0.0015                                           (B) 0.003 
(C) 0.048                                            (D) 0.768 
4. A spherical black body with a radius of 12 cm radiates 450 W power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be: 
(A) 225                                              (B) 450 
(C) 900                                              (D) 1800 
5. A proton, a deuteron and an α-particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If rp, rd and rα denote respectively the radii of the trajectories of these particles, then: 
(A) rα = rp is l.t. rd                                    (B) rα > rd > rp 
(C) rα = rd is l.t. rp                                    (D) rp = rd = rα 
Source 1997 JEE
Sunday, October 11, 2009
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