Multiple Choice QuestionsOne mole of ideal monoatomic gas (γ = 5/30) is mixed with one mole of diatomic gas(γ = 7/5). What is γ for the mixture? γ denotes the ratio of specific heat at constant pressure, to that at constant volume.
3/2
23/15
35/23
35/23
If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be
4
16
32
32
Which of the following statements is correct for any thermodynamic system?
The internal energy changes in all processes.
Internal energy and entropy are state functions.
The change in entropy can never be zero.
The change in entropy can never be zero.
Two thermally insulated vessels 1 and 2 are filled with air at temperatures (T1, T2), volume (V1, V2) and pressure (P1, P2) respectively. If the valve joining two vessels is opened, the temperature inside the vessel at equilibrium will be
T1 + T2
T1Â + T2/2
A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is
E/c
2E/c
The temperature of two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity K and 2K and thickness x and 4x, respectively are T2 and T1 (T2 > T1). The rate of heat transfer through the slab, in a steady state is
 with f, equal to
1
1/2
2/3
2/3
A light ray is incident perpendicular to one face of a 90° prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45°, we conclude that the refractive index n
n<2
Time taken by a 836 W heater to heat one litre of water from 10°C to 40°C is
50 s
100 s
150 s
150 s
C.
150 s
Let time taken in boiling the water by the heater is t sec. Then
Q = ms ∆ T
The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = a θ + bθ2 in volts where the ratio a/b is 700°C. If the cold junction is kept at 0°C, then the neutral temperature is
700°C
350°C
1400°C
1400°C
A charged particle q is shot towards another charged particle Q which is fixed, with a speed v it approaches Q upto a closest distance r and then returns. If q were given a speed 2v, the closest distances of approach would be
r
2r
r/2
r/2
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