Heat and Thermodynamics · Physics · AIIMS

The temperature of food material in refrigerator is 4$$^\circ$$C and temperature of environment is 15$$^\circ$$C. If carnot cycle is used in its working gas, then find its carnot efficiency.

If $$7 \mathrm{~gm} \mathrm{~N}_2$$ is mixed with $$20 \mathrm{~gm} \mathrm{~Ar}$$, there $$\frac{C_p}{C_V}$$ of mixture will be

In an isobaric process, the work done by a di-atomic gas is 10 J, the heat given to the gas will be

Calculate radiation power for sphere whose temperature is 227$$^\circ$$C, radius 2 m and emissivity 0.8.

An ideal gas initially at pressure 1 bar is being compressed from $$30 \mathrm{~m}^3$$ to $$10 \mathrm{~m}^3$$ volume and its temperature decreases from $$320 \mathrm{~K}$$ to $$280 \mathrm{~K}$$, then find final pressure of the gas.

Assertion : Vibrational degree of freedom of a di-atomic gas molecule appears at every high temperature.

Reason : Di-atomic gas has two vibrational degree of freedom in one direction.

Assertion : $$\mathrm{NH}_3$$ is liquidities more easily than $$\mathrm{CO}_2$$.

Reason : Critical temperature of $$\mathrm{NH}_3$$ is more than $$\mathrm{CO}_2$$.

Assertion : In adiabatic process work is independent of the path.

Reason : In adiabatic process work done is equal to negative of change in internal energy.

An ideal gas of mass $$m$$ in a state $$A$$ goes to another state $$B$$ via three different processes as shown in figure. If $$Q_1, Q_2$$ and $$Q_3$$ denote the heat absorbed by the gas along the three paths, then

A gas consisting of a rigid diatomic molecules was initially under standard condition. Then, gas was compressed adiabatically to one-fifth of its initial volume. What will be the mean kinetic energy of a rotating molecule in the final state?

Assertion In isothermal process, whole of the heat energy supplied to the body is converted into internal energy.

Reason According to the first law of thermodynamics,

$$\Delta Q=\Delta U+\Delta W$$

Assertion Internal energy of an ideal gas does not depend on volume of gas.

Reason Internal energy depends only on temperature of gas.

The coefficient of cubical expansion of mercury is $$0.00018 /{ }^{\circ} \mathrm{C}$$ and that of brass $$0.00006 /{ }^{\circ} \mathrm{C}$$. If a barometer having a brass scale were to read $$74.5 \mathrm{~cm}$$ at $$30^{\circ} \mathrm{C}$$, find the true barometric height at $$0^{\circ} \mathrm{C}$$. The scale is supposed to be correct at $$15^{\circ} \mathrm{C}$$.

One mole of an ideal diatomic gas undergoes transition from A to B along a path AB as shown below.

The change in internal energy of the gas during the transition is

Assertion : It is hotter over the top of a fire than at the same distance on the sides.

Reason : In the upward direction, the heat propagate through convection.

Assertion : In adiabatic expansion the product of $$p$$ and $$V$$ always decreases.

Reason : In adiabatic expansion process, work is done by the gas at the cost of internal energy of gas.

Assertion : The molecules of a monoatomic gas has three degrees of freedom.

Reason : The molecules of diatomic gas has five degrees of freedom.

Assertion : Molar heat capacity cannot be defined for isothermal process.

Reason : In isothermal process $$p$$-$$V$$ versus $$T$$ graph is a dot.