Thermodynamics PYQ — Page 2

The efficiency of a Carnot engine depends upon

A cylinder contains hydrogen gas at pressure of $249\mathrm{kPa}$ and temperature ${27}^{o}C$. Its density is: $(R=8.3\mathrm{JK}{\mathrm{Mol}}^{-1}{K}^{-1})$

The quantities of heat required to raise the temperature of two solid copper spheres of radii ${r}_{1}$ and ${r}_{2}({r}_{1}=1.5 {r}_{2})$ through $1 K$ are in the ratio:

The mean free path $l$ for a gas molecule depends upon diameter, $d$ of the molecule as:

The $P-V$ diagram for an ideal gas in a piston cylinder assembly undergoing a thermodynamic process is shown in the figure. The process is 

An ideal gas equation can be written as, $P=\frac{\rho RT}{{M}_{0}}$ where $\rho$ and ${M}_{0}$ are respectively,

Three stars $A,B,C$ have surface temperatures ${T}_{A},{T}_{B},{T}_{C}$ respectively. Star A appears bluish, star $B$ appears reddish and star $C$ yellowish. Hence,

The average thermal energy for a mono-atomic gas is : (${k}_{B}$ is Boltzmann constant and $T$, absolute temperature)

The value of $\gamma\left(=\frac{C_p}{C_V}\right)$ for hydrogen, helium and another ideal diatomic gas $\mathrm{X}$ (whose molecules are not rigid but have an additional vibrational mode), are respectively equal to

1 g of water, of volume $1 \mathrm{~cm}^3$ at $100^{\circ} \mathrm{C}$ is converted into steam at same temperature under normal atmospheric pressure $=\left(\simeq 1 \times 10^5 \mathrm{~Pa}\right)$. The volume of steam formed equals $1671 \mathrm{~cm}^3$. If the specific latent heat of vaporisation of water is $2256 \mathrm{~J} / \mathrm{g}$, the change in internal energy is

In which of the following processes, heat is neither absorbed nor released by a system?

Increase in temperature of a gas filled in a container will leads to

A deep rectangular pond of surface area $\mathrm{A}$, containing water (density $=\rho$, specific heat capacity $=s$ ), is located in a region where the outside air temperature is a steady value at the $-26^{\circ} \mathrm{C}$. The thickness of the frozen ice layer in this pond, at a certain instant is $\mathrm{x}$. Taking the thermal conductivity of ice as $\mathrm{K}$, and its specific latent heat of fusion as L, the rate of increase of the thickness of ice layer, at this instant would be given by

An object kept in a large room having air temperature of $25^{\circ} \mathrm{C}$ takes 12 minutes to cool from $80^{\circ} \mathrm{C}$ to $70^{\circ} \mathrm{C}$. The time taken to cool for the same object from $70^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ would be nearly

A copper rod of $88 cm$ and an aluminum rod of unknown length have their increase in length independent of increase in temperature. The length of aluminum rod is $({\alpha }_{Cu}=1.7\times {10}^{-5}{K}^{-1} and {\alpha }_{\mathrm{Al}}=2.2\times {10}^{-5} {K}^{-1})$

The power radiated by a black body is P and it radiates maximum energy at wavelength, ${\lambda }_{0}$. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength $\frac{3}{4}{\lambda }_{0}$, the power radiated by it becomes nP. The value of n is

At what temperature will the rms speed of oxygen molecules becomes just sufficient for escaping from the Earth's atmosphere? (Given Mass of oxygen molecules $m=2.76\times {10}^{-26} kg$, Boltzmann's constant ${k}_{B}=1.38\times {10}^{-23} J {K}^{-1}$)

The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is

A sample of $0.1 \text{g}$ of water at ${100}^{ o}C$ and normal pressure $(1.013\times {10}^{5} N{ m}^{-2})$ requires $54 \text{cal}$ of heat energy to convert to steam at ${100}^{ o}C$. If the volume of the steam produced is $167.1 \text{cc,}$ the change in internal energy of the sample, is

The Volume $(V)$ of a monoatomic gas varies with its temperature $(T)$, as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state $A$ to state $B$, is 

A spherical black body with a radius of $12\mathrm{cm}$ radiates $450W$ power at $500K$. If the radius were halved and the temperature doubled, the power radiated in watt would be

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

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are ${K}_{1}$ and ${K}_{2}$. The thermal conductivity of the composite rod will be 

A gas mixture consists of $2$ moles of ${O}_{2}$ and 4 moles of $Ar$ at temperature $T$. Neglecting all vibrational modes, the total internal energy of the system is ($R$ is universal gas constant)