The efficiency of a Carnot engine is 40% when it receives energy at 500 K. At what temperature it should receive energy  to increase its efficiency by 25% ?

1.	600 K	2.	700 K
3.	800 K	4.	900 K

Find out the total heat given to diatomic gas in the process A$\to$B$\to$C : (B$\to$C is isothermal)
                 

1. ${\mathrm{P}}_0{\mathrm{V}}_0+2{\mathrm{P}}_0{\mathrm{V}}_0$ $\ln 2$

2. $\frac{1}{2}$${\mathrm{P}}_0{\mathrm{V}}_0+2{\mathrm{P}}_0{\mathrm{V}}_0\ln 2$

3. $\frac{5}{2}$${\mathrm{P}}_0{\mathrm{V}}_0+2{\mathrm{P}}_0{\mathrm{V}}_0$ $\ln 2$

4. 3${\mathrm{P}}_0{\mathrm{V}}_0+2{\mathrm{P}}_0{\mathrm{V}}_0$ $\ln 2$

When a bicycle tyre suddenly bursts, the air inside the tyre expands. This process is:

Two cylinders, A and B, of equal capacity are connected to each other via a stopcock. A contains gas at a standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. If the stopcock is suddenly opened, then the change in internal energy of the gas is:

Which of the following is true for the molar heat capacity of an ideal gas?

0.04 mole of an ideal monatomic gas is allowed to expand adiabatically so that its temperature changes from 800 K to 500 K. The work done during expansion is nearly equal to:

A refrigerator whose coefficient of performance is 5 extracts heat from the cooling chamber at a rate of 250 J per cycle. For refrigeration, the work done per cycle is:

1. 150 J

2. 200 J

3. 100 J

4. 50 J

The internal energy of an ideal gas increases in:

1. Adiabatic expansion

2. Adiabatic compression

3. Isothermal expansion

4. Isothermal compression

If an ideal gas undergoes two processes at constant volumes ${\mathrm{V}}_1$ $\mathrm{and}$ ${\mathrm{V}}_2$ as shown in the pressure-temperature (P-T) diagram, then:

1. ${\mathrm{V}}_1$ = ${\mathrm{V}}_2$

2. ${\mathrm{V}}_1$ > ${\mathrm{V}}_2$

3. ${\mathrm{V}}_1$ < ${\mathrm{V}}_2$

4. ${\mathrm{V}}_1\ge {\mathrm{V}}_2$

A heat engine is working between 200 K and 400 K. The efficiency of the heat engine may be:

1. 20%

2. 40%

3. 50%

4. All of these