# JEE Class main Answered

**Solve**

Asked by sarveshvibrantacademy | 14 May, 2019, 09:57: AM

Expert Answer

Let us assume the initial state of 1 mole of ideal monoatomic gas as pressure P

_{0}, Volume V_{0}and Temperature T_{0}At Initial state, Internal energy of ideal monoatomic gas = (3/2)nRT

_{0}..............(1)where n is number of moles, R is universal gas constant. Hence we have (3/2)RT

_{0}= 18000 J ..................(2)The gas undergoes intermediate state by isochoric process (volume constant) so that intermediate state pressure is P

_{0}/3.For ideal gas, when volume is constant, Pressure is proportional to Temperature.

Hence in Intermediate state Temperature becomes T

_{0}/3 .Hence internal energy at intermediate state = (3/2)R(T

_{0}/3) = 18000/3 = 6000 J ...................(3)[ eqn.(2) is used in eqn.(3) to get internal energy at intermediate state ]

Change in internal energy dU from initial state to intermediate state = 6000 -18000 = -12000 J

Since volume is constant in isochoric process, workdone dw = 0 and Heat released dQ to cool from

temperature T

_{0}to (T_{0}/3 ) is equal to change in internal energy duHence from initial state to intermediate state, dQ = du = -12000 J ...............................(4)

Now the gas undergoes isobaric process (pressure constant) to reach a final state so that

final state temeperature is same as Initial state temperature T

_{0}.For ideal gas, when pressure is constant, volume is proportional to temperature.

From intermediate state to final state, temperature changes from (T

_{0}/3) to T_{0}.Hence from intermediate state to final state,Volume changes from V

_{0}to 3V_{0 }. ( V/T is constant)Workdone dW by the gas is given by, dW = (P

_{0}/3) [ 3V_{0}- V_{0}] = (2/3)P_{0}V_{0}= (2/3) RT_{0}.......................(5)using eqn.(2) and eqn.(5), we get dW = 8000 J ........................(6)

when the gas reaches final state, temperature of final state is same as that of initial state, i.e., T

_{0}Since internal energy is related only to temperature and number of moles, final state internal energy = 18000 J.

Hence change in internal energy dU from intermediate state to final state is given by, dU = 18000 - 6000 = 12000 J

From first law of thermodynamics, we get the absorbed heat dQ as given by ,

dQ = dU + dW = 12000 +8000 = 20000 J ..........................(7)

from eqn.(4) and eqn.(7), net amount of heat energy absorbed = -12000 + 20000 = 8000 J

Answered by Thiyagarajan K | 14 May, 2019, 09:29: PM

## Application Videos

JEE main - Physics

Asked by btennyson663 | 13 Jun, 2024, 08:02: PM

ANSWERED BY EXPERT

JEE main - Physics

Asked by sonakshiswami0 | 12 Jun, 2024, 10:29: PM

ANSWERED BY EXPERT

JEE main - Physics

Asked by ishnica7 | 12 Jun, 2024, 08:04: PM

ANSWERED BY EXPERT

JEE main - Physics

Asked by gbharat875 | 07 Jun, 2024, 07:15: AM

ANSWERED BY EXPERT

JEE main - Physics

Asked by amritsheet | 30 May, 2024, 08:28: PM

ANSWERED BY EXPERT

JEE main - Physics

Asked by lalamsurya41 | 27 May, 2024, 10:37: AM

ANSWERED BY EXPERT