We consider a thermodynamic system. If ΔU represents the increase in its internal energy and W the work done by the system, which of the following statements is true ?

1. ΔU = –W in an adiabatic process

2. ΔU = W in an isothermal process

3. ΔU = –W in an isothermal process

4. ΔU = W in an adiabatic process

The volume of a gas is reduced adiabatically to $\frac{1}{4}$ of its volume at 27°C, if the value of γ = 1.4, then the new temperature will be - 

(1) 350 × 4^0.4 K

(2) 300 × 4^0.4 K

(3) 150 × 4^0.4 K

(4) None of these

For an adiabatic expansion of a perfect gas, the value of $\frac{\Delta P}{P}$ is equal to 

(1) $-\sqrt{\gamma }\frac{\Delta V}{V}$

(2) $-\frac{\Delta V}{V}$

(3) $-\gamma \frac{\Delta V}{V}$

(4) $-{\gamma }^2\frac{\Delta V}{V}$

One mole of a perfect gas in a cylinder fitted with a piston has a pressure P, volume V and temperature 273 K. If the temperature is increased by 1 K keeping pressure constant, the increase in volume is

(1) $\frac{2V}{273}$

(2) $\frac{V}{91}$

(3) $\frac{V}{273}$

(4) V

A unit mass of a liquid with volume V₁ is completely changed into a gas of volume V₂ at a constant external pressure P and temperature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is: 
1.  Zero
2. $P(V_2-V_1)$
3. $L-P(V_2-V_1)$
4.  L

If 300 ml of a gas at 27°C is cooled to 7°C at constant pressure, then its final volume will be -

(1) 540 ml

(2) 350 ml

(3) 280 ml

(4) 135 ml

If the door of a refrigerator is kept open, then which of the following is true ?

1. Room is cooled

2. Room is heated

3. Room is either cooled or heated

4. Room is neither cooled nor heated

A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are 411°C and 69°C respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is -

(1) 100 J

(2) 300 J

(3) 500 J

(4) 700 J

The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is -

(1) 300 K

(2) 400 K

(3) 500 K

(4) 700 K

Efficiency of a Carnot engine is 50% when temperature of outlet is 500 K. In order to increase efficiency up to 60% keeping temperature of intake the same what is temperature of outlet ?

(1) 200 K

(2) 400 K

(3) 600 K

(4) 800 K