NEET UG 2015 — Thermodynamics

A Carnot engine, having an efficiency of $\eta =\frac{1}{10}$ as heat engine, is used as a refrigerator. If the work done on the system is $10J$, the amount of energy absorbed from the reservoir at a lower temperature is:

An ideal gas is compressed to half of its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?

Figure below shows two paths that may be taken by a gas to go from a state A to a state C.  In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be:

$4.0 g$ of a gas occupies $22.4$ liters at NTP. The specific heat capacity of the gas at constant volume is $5.0 J{K}^{-1} mo{l}^{-1}$ . If the speed of sound in this gas at NTP is $952 m{s}^{-1}$ , then the heat capacity at constant pressure is (Take gas constant $R=8.3 J{K}^{-1} mo{l}^{-1}$ )

On observing light from three different stars $\text{P}$ , $\text{Q}$ and $\text{R}$ , it was found that intensity of violet colour is maximum in the spectrum of $\text{P}$ , the intensity of green colour is maximum in the spectrum of $\text{R}$ and the intensity of red colour is maximum in the spectrum of $\text{Q}$ . If ${T}_{p}, {T}_{Q}$ and ${T}_{R}$ are the respective absolute temperatures of $\text{P}$ , $\text{Q}$ and $\text{R}$ , then it can be concluded from the above observations that :

One mole of an ideal diatomic gas undergoes a transition from $A$ to $B$ along a path $\mathrm{AB}$ as shown in the figure,  The change in internal energy of the gas during the transition is:

The coefficient of performance of a refrigerator is $5$. If the temperature inside the freezer is $-20^{\circ}C$, the temperature of the surrounding to which it rejects heat is:

The ratio of the specific heats $\frac{{C}_{P}}{{C}_{v}}= \gamma$ in terms of degrees of freedom (n) is given by:

The two ends of a metal rod are maintained at temperatures $100 ^{\circ}C$ and $110 ^{\circ}C$ . The rate of heat flow in the rod is found to be $4.0{\text{J s}}^{-1}$ . If the ends are maintained at temperatures $200 ^{\circ}C$ and $210 ^{\circ}C$ , the rate of heat flow will be:

Two vessels separately contain two ideal gases $A$ and $B$ at the same temperature, the pressure of $A$ being twice that of $B$. Under such conditions, the density of $A$ is found to be $\text{1.5}$ times the density of $B$. The ratio of molecular weights of $A$ and $B$ is