Thermodynamics PYQ — Page 3

Thermodynamic processes are indicated in the following diagram.  Match the following <table class="pyq-table"><tbody><tr><td>Column – 1</td><td>Column - 2</td></tr><tr><td>P. Process I</td><td>a. Adiabatic</td></tr><tr><td>Q. Process II</td><td>b. Isobaric</td></tr><tr><td>R. Process III</td><td>c. Isochoric</td></tr><tr><td>S. Process IV</td><td>d. Isothermal</td></tr></tbody></table>

Coefficient of linear expansion of brass and steel rods are ${\alpha }_{1}$ and ${\alpha }_{2}$. Lengths of brass and steel rods are ${l}_{1}$ and ${l}_{2}$, respectively. If $({l}_{2}-{l}_{1})$ is maintained the same at all temperatures, which one of the following relations holds good?

A body cools from a temperature $3T$ to $2T$ in $10$ minutes. The room temperature is $T$. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next $10$ minutes will be

A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then:

Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at ${100}^{ o}C$, while the other one is at ${0}^{ o}C$. If the two bodies are brought into contact, then assuming no heat loss, the final common temperature is

The molecules of a given mass of gas have RMS velocity of $200$ $m {s}^{-1}$ at ${27}^{o}C$ and $1.0\times {10}^{5} N {m}^{-2}$ pressure. When the temperature and pressure of the gas are respectively, ${127}^{o}C$ and $0.05\times {10}^{5} N {m}^{-2}$, the r.m.s. velocity of its molecules in $m {s}^{-1}$ is:

A given sample of an ideal gas occupies a volume, $V$ at a pressure, $P$ and absolute temperature, $T$. The mass of each molecule of the gas is $\text{m}$. Which of the following gives the density of the gas?

A black body is at a temperature of $\text{5760}\text{ K.}$ The energy of radiation emitted by the body at wavelength $\text{250}\text{ nm}$ is ${U}_{1}$, at wavelength $\text{500} \text{ nm}$ is ${U}_{2}$ and that at $\text{1000}\text{ nm}$ is ${U}_{3}$. Wien's constant, $b=2.88\times {10}^{6}\text{ nm K.}$ Which of the following is correct?

A refrigerator works between ${4}^{o }C$ and ${30}^{o}C$. It is required to remove $\text{600}$ calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is: (Take $\text{1}$ cal = $\text{4}\text{.2}$ Joules)

One mole of an ideal monatomic gas undergoes a process described by the equation $\text{P}{\text{V}}^{3}=$ constant. The heat capacity of the gas during this process is

A piece of ice falls from a height $h$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of $h$ is: (Latent heat of ice is $3.4\times {10}^{5} {\text{J kg}}^{-1}$ and $g=10 {\text{N kg}}^{-1}$)

The temperature inside a refrigerator is ${t}_{2}{ }^{o}C$ and the room temperature is ${t}_{1}{}^{o}C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be

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:

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?

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

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 :

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:

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:

$4.0 g$ 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 $R=8.3 J{K}^{-1} mo{l}^{-1}$ )

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:

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:

A thermodynamics system undergoes cyclic process $ABCDA$ as shown in Figure. The work done by the system in the cycle is: 

Steam at ${100 }^{o}C$ is passed into $20 g$ of water at ${10 }^{o}C.$ When water acquires a temperature of ${80}^{o}C,$ the mass of water present will be: [Take specific heat of water $=1 cal {g}^{-1 o}{C}^{-1}$ and latent heat of steam $=540 cal {g}^{-1}]$