Assignment 3 on heat and thermodynamics (Multiple choice type questions)

Question 1: What increase in radiated power results when the temperature of a blackbody is increased from 7 to 287 0 C

a)  4

b) 8

c) 16

d) None of these

Question 2: The internal energy of an ideal gas depends on

a) Temperature

b) Pressure

c) Volume

d) None of these


Question 3:     

All Rod are of equal length and equal area of crossection.Find the temperature at point B
a,     45          
b,     51.4
c,     50          
d,     51


Question 4:
An ideal gas is taken through a cyclic thermodynamics process through four steps.
The amount of heat involved in the steps are Q1 = 5960 J,Q2 = - 5600 J,Q3= -3000 J,Q4 = -3600 J
respectively. The corresponding quantities of Internal energy changes are ΔU1 = 3.760 J ,ΔU2 = - 4800 J,ΔU3 = -1800 J,ΔU4 = ?
find the value ΔU4 & net work done
a, 2930 J, 960 J          
b, 2830 J, 900 J
C, 2930 J, -960 J
d, -2930 J, 960 J



Question 5:

4 moles of an ideal gas undergoes an isothermal expansion at temperature T during which the volume becomes η times.

W -> Workdone by the gas

 -> Change in internal energy












Q-6  M moles  of a ideal polyatomic gas(Cv=7R/2)  are in cylinder at temperature T.A heat Q is suuplied to the gas. Some M/3 moles of the gas dissociated into atoms while temperature remains constant. Find the correct relation

a) 3Q=4MRT


 b) 2Q=3MRT


c) Q=4MRT


d) 7Q=4MRT



Q-7 Absorbing power of the surface is .7. Transmitting power of the surface is .1

A total heat Q is incident on the surface. Find the heat reflected back?



c) Q/2

d) Q/5


A hole of radius R1 is made centrally in a circular disc of thickness d and radius R2.The inner surface is maintained at temperature T1 and other surface is maintained at T2 (T1 > T2).Thermal conductivity of the circular plate is K.
a. Find the temperature as a function of radius from centre
b. Find the heat flow per unit time



Assertion and Reason
a) Statement I is true ,statement II is true ,statement II is correct explanation for statement I
b) Statement I is true ,statement II is true ,statement II is not a correct explanation for statement I
c) Statement I is true, Statement II is false
d) Statement I is False, Statement II is True

STATEMENT 1:The molar specific heat capacity of the ideal gas in isothermal process is infinity
STATEMENT 2:Heat transfer is non zero in the Isothermal process

STATEMENT 1:Equation of state for a real gas is (P+a/V2)(V-b)=nRT
STATEMENT 2: Molecular attraction is not neglible and the size of molecules are not neglibile in comparison to average separation between them


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