NEET UG 2016 — Thermodynamics

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 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:

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 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 $g=10 {\text{N kg}}^{-1}$)

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)

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?

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

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:

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

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