MEDIUM
JEE Main/Advance
IMPORTANT
Earn 100

In the given figure an ideal gas changes its state from A to state C by two paths ABC and AC.

Question Image

(i) The internal energy of gas at A is 10 J and amount of heat supplied to change its state to C through the path AC is 200 J. Calculate the internal energy at C.

(ii) The internal energy of gas at B is 20 J. Find the amount of heat supplied to the gas from A to B.

Important Questions on Thermodynamics

HARD
JEE Main/Advance
IMPORTANT
The pressure in monoatomic gas increases linearly from 4×105 N m-2 to 8×105 N m-2 when its volume increases from 0.2 m3 to 0.5 m3.

(i) If work done by the gas is 1.8×10y J then find the value of y.

(ii) If increase in internal energy is 1.6z×105 J then find the value of z.

(iii) If amount of heat supplied is 6.6×10x J then find the value of x.

(iv) If molar specific heat of the gas is 1.71×10α J mole-K-1 then find the value of α.

EASY
JEE Main/Advance
IMPORTANT
On mole of a monoatomic ideal gas is taken through the cycle shown in figure.

Question Image 

AB : Adiabatic expansion            BC : Cooling at constant volume 

CD : Adiabatic compression

DA : Heating at constant volume

The pressure and temperature at A, B, etc., are denoted by PA,TA,PB,TB etc., respectively. Given that TA=1000 KPB=23PA and PC=13PA.

Calculate the following quantities : (i) The work done by the gas in the process AB

(ii) The heat lost by the gas in the process BC

(iii) The temperature TD. (Given : 232/5=0.85)

EASY
JEE Main/Advance
IMPORTANT

At 27º C two moles of an ideal monoatomic gas occupy a volume V. The gas expands adiabatically to a volume 2V. Calculate:

(i) the final temperature of the gas,

(ii) change in its internal energy and 

(iii) the work done by the gas during the process.

HARD
JEE Main/Advance
IMPORTANT
Three moles of an ideal gas CP=72R at pressure, PA and temperature TA is isothermally expanded to twice its initial volume. It is then compressed at constant pressure to its original volume. Finally gas is compressed at constant volume to its original pressure PA. If the net work done by the gas, and net heat support to the gas during the complete process is x and y respectively then fine xy.
MEDIUM
JEE Main/Advance
IMPORTANT
Two moles of helium gas γ=5/3 are initially at temperature 27°C and occupy a volume of 20 L. The gas is first expanded at constant pressure until the volume is doubled. Then it undergoes an adiabatic change until the temperature returns to its initial value. (i) If the final volume and pressure of the gas are 1.13×10αL and 4.4×10β N m-2 then the find α+β. (ii) What is the work done by the gas?
MEDIUM
JEE Main/Advance
IMPORTANT
Calculate the work done (in joule) when 1 mole of a perfect gas is compressed adiabatically. The initial pressure and volume of the gas are 105N m-2 and 6 litre respectively. The final volume of the gas is 2 litre. Molar specific heat of the gas at constant volume is 3R/2. [35/3=6.19]
EASY
JEE Main/Advance
IMPORTANT
A gaseous mixture enclosed in a vessel of volume V consists of one gram mole of gas. A with γ=CPCV=53 an another gas B with γ=75 at a certain temperature T. The gram molecular weight of the gases A and B are 4 and 32 respectively. The gases A and B do not react with each other and are assumed to be ideal. The gaseous mixture follows the equation PV19/13= constant, in adiabatic process. Find the number of gram moles of the gas B in the gaseous mixture.
EASY
JEE Main/Advance
IMPORTANT
An ideal gas is taken through a cyclic thermodynamic process through four steps. The amount of heat involved in these steps are Q1=5960J,Q2=-5585J,Q3=-2980J and Q4=3645J, respectively. The corresponding works involved are W1=2200J, W2=-825J, W3=-1100J and W4.
(a) Find the value of W4 .
(b) What is the efficiency of the cycle?