86. If a wave guide is perfect conductor, then the boundary conditions at its inner walls are (1) E 0, B =0 = (2) E 0, B#0 (3) E0, B=0 (4) E0, B10 87. The energy of an ideal boson gas below condensation temperature is proportional to (1) T1/2 (2) T3/2 (3) T5/2 (4) T7/2 88. If Im [f(0-0)] is the imaginary part of th forward scattering amplitude, then the optical theorem is [Total Total cross section] 4 (1) Total Im [f(0 = 0)] k 4m (2) Total Im [f(0 = 0)] 4 (3) Total f(0-0)| = 4 (4) Total |f(0 = 0)| 89. For the adder circuit shown output. voltage is -2v ww -3V www 8 2 kQ +4V (1) 2 volts (2) 10 volts (3) 36 volts (4) 4 volts 90. Using nuclear shell model the ground 17, state spin and parity of O is (1) (3) 52 3/2 (2) (4) 3/2