Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

By the definition of $${C_V}$$ we can write $${C_V} = \mathop {\lim }\limits_{\delta T \to 0} {\left( {\frac{{\delta Q}}{{\delta T}}} \right)_V}.$$
Since, under constant volume process the expansion work is zero, and by first law of thermodynamics
$$\eqalign{ & \delta Q = dU \cr & \Rightarrow {\left( {\frac{{\partial U}}{{\partial T}}} \right)_V} = {C_V}. \cr} $$

By the definition of $${C_P}$$ we can write $${C_P} = \mathop {\lim }\limits_{\delta T \to 0} {\left( {\frac{{\delta Q}}{{\delta T}}} \right)_P}.$$
Under constant pressure process and by first law of thermodynamics
$$\eqalign{ & Q = dH \cr & \Rightarrow {\left( {\frac{{\partial H}}{{\partial T}}} \right)_P} = {C_P}. \cr} $$

Joule-thomson coefficient is nothing but the slope graph between temperature and pressure which is a plot obtained experimentally under constant enthalpy conditions $${\left( {\frac{{\partial T}}{{\partial P}}} \right)_H} = \mu .$$
There is huge significance for this and is used to tell whether a fluid undergoes cooling or heating by throttling.

A refrigeration cycle is just the reverse of heat engine where it takes heat from low temperature reservoir and gives to high temperature reservoir.

Heat of reaction is dependent on both pressure and temperature.

Let's analyze each option to determine the correct statement:

Option A: Entropy and enthalpy are path functions.

This statement is incorrect. Entropy and enthalpy are both state functions, not path functions. State functions depend only on the current state of the system and are independent of the path taken to reach that state.

Option B: In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged.

This statement is correct. In a closed system, energy can be exchanged with the surroundings (through heat or work), but matter cannot enter or leave the system.

Option C: All the natural processes are reversible in nature.

This statement is incorrect. In reality, most natural processes are irreversible. Reversible processes are idealized and often used in thermodynamics for analysis, but they are not the norm in the real world.

Option D: Work is a state function.

This statement is incorrect. Work is not a state function; it is a path function. The amount of work done depends on the specific path taken during a process.

Therefore, the correct statement among the options is Option B: In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged.

We know from second law of thermodynamics that all the reversible engines working under the same temperature reservoirs have same efficiency. Since Carnot engine is an reversible engine. So, the efficiency of a Carnot engine doesn’t depends upon the working fluid involved. It just depends upon the temperatures of then reservoirs involved.

The basic function of the heat pump is to transfer heat from low temperature reservoir to high temperature reservoir by taking the external help. So, it always accomplishes heating of the surroundings.

Since, every fluid at $$S.T.P$$ occupies $$22.4\,\,ltrs$$   of volume per unit mole.
Here given number of moles $$ = \frac{{{\text{weight}}}}{{{\text{gram molecular weight}}}} = 20$$
So, the volume occupied $$ = 22.4 * 20 = 448\,\,ltrs.$$

The ability to transfer heat is thermal conductivity and usually the metals have higher thermal conductivity and diamond being crystalline substance has highest thermal conductivity. In the given options the molten sodium has highest thermal conductivity.