One mole of helium is adiabatically expanded from its initial state $(P_i,V_i,T_i)$ to its final state $(P_f,V_f,T_f)$. The decrease in the internal energy associated with this expansion is equal to

(1) $C_V(T_i-T_f)$

(2) $C_P(T_i-T_f)$

(3) $\frac{1}{2}(C_P+C_V)(Ti-T_f)$

(4) $(C_P-C_V)(T_i-T_f)$

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 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

In a cyclic process, the internal energy of the gas:

The efficiency of Carnot's engine operating between reservoirs, maintained at temperatures 27°C and –123°C, is 

(1) 50%

(2) 24%

(3) 0.75%

(4) 0.4%

When an ideal gas (γ = 5/3) is heated under constant pressure, then what percentage of given heat energy will be utilised in doing external work ?

1. 40 %

2. 30 %

3. 60 %

4. 20 %

An ideal monoatomic gas expands in such a manner that its pressure and volume can be related by equation \(PV^{5/3}=\text{constant}.\) During this process, the gas is:

1. Heated

2. Cooled

3. Neither heated nor cooled

4. First heated and then cooled

Which of the following graphs correctly represents the variation of $\beta =-(dV/dP)/V$ with P for an ideal gas at constant temperature ?

(1)

(2)

(3)

(4)

A cyclic process for \(1\) mole of an ideal gas is shown in the \(V\text-T\) diagram. The work done in \(AB, BC\) and \(CA\) respectively is:

The Carnot cycle (reversible) of gas is represented by a pressure-volume curve as shown in the figure. Consider the following statements:

Which of the statement(s) given above is/are correct?