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

1.	\(\Delta \mathrm{U}=-\mathrm{W}\)  in an isothermal process
2.	\(\Delta \mathrm{U}=\mathrm{W}\) in an isothermal process
3.	\(\Delta \mathrm{U}=-\mathrm{W}\) in an adiabatic process
4.	\(\Delta \mathrm{U}=\mathrm{W}\)  in an adiabatic process

The initial pressure and volume of a gas are P and V respectively. First, its volume is expanded to 4V by an isothermal process and then compressed adiabatically to volume V. The final pressure will be (γ = 1.5):
1.  8P
2.  4P
3.  P
4.  2P

One mole of an ideal gas at an initial temperature of \(T\) K does \(6R\) joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is \(5/3\), the final temperature of the gas will be:
1. \((T-2.4)\) K
2. \((T+4)\) K
3. \((T-4)\) K
4. \((T+2.4)\) K

If a gas changes volume from 2 litres to 10 litres at a constant temperature of 300K, then the change in its internal energy will be:

When volume changes from \(V\) to \(2V\) at constant pressure(\(P\)), the change in internal energy will be:
1. \(PV\)
2. \(3PV\)
3. \(\frac{PV}{\gamma -1}\)
4. \(\frac{RV}{\gamma -1}\)

An ideal gas heat engine operates in a Carnot cycle between 227ºC and 127ºC. It absorbs 6 × 10⁴ cals of heat at higher temperatures. The amount of heat converted to work will be?
1. 4.8 × 10⁴ cals
2. 2.4 × 10⁴ cals
3. 1.2 × 10⁴ cals
4. 6 × 10⁴ cals

Which one of the following processes is reversible?