Physics Thermodynamics questions from NEET UG 2017.
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
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)
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
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>
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 