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Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

Learn Chemical Engineering Thermodynamics MCQ questions & answers are available for a Chemical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Chemical Engineering Thermodynamics MCQ question is the important chapter for a Chemical Engineering and GATE students. Page-5 section-1

Each section contains 100 MCQs on Chemical Engineering Thermodynamics .
41
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
Discuss
Answer & Solution
Answer: Option D
Solution:
Given, number of components $$= 2$$
Number of phases $$= 1$$
So, degree of freedom
\[\begin{array}{l} f = C - \emptyset + 2\\ \Rightarrow 2 - 1 + 2\\ \Rightarrow 3\\ F = 3 \end{array}\]
42
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
Discuss
Answer & Solution
Answer: Option B
Solution:
Since here heat is taken from the system \[Q = - ve\]
From second law of thermodynamics \[TdS \ge \delta Q\]
Since given reversible process \[TdS = \delta Q\]
$$ \Rightarrow dS = - ve$$
From first law of thermodynamics
$$\eqalign{ & \delta Q = dU \cr & \Rightarrow dU = - ve \cr} $$
43
The expression for entropy change given by, $$\Delta S = - nRln\left( {\frac{{{P_2}}}{{{P_1}}}} \right),$$    holds good for
Discuss
Answer & Solution
Answer: Option B
Solution:
We know $$S$$ as a function of $$T$$ and $$P$$ as :
$$dS = \frac{{{C_P}dT}}{T} - {\left( {\frac{{\partial V}}{{\partial T}}} \right)_P}dP$$
For isothermal change $$dT = 0$$   for ideal gas $$\frac{{\partial V}}{{\partial {T_P}}} = \frac{{nR}}{P}$$
$${\text{So, }}dS = - nRln\left( {\frac{{{P_2}}}{{{P_1}}}} \right)$$
For isothermal volume change of an ideal gas for both reversible and irreversible process.
44
For any system, what is the minimum number of degrees of freedom?
Discuss
Answer & Solution
Answer: Option B
Solution:
The degree of freedom means the minimum number of intensive variables which are needed to specify the system and its minimum value is zero.
Triple point of a substance is one of the state for which the degree of freedom $$= 0.$$
45
Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants)
Discuss
Answer & Solution
Answer: Option D
Solution:
The equilibrium constant $$\left( {{K_P}} \right)$$   for the reaction below can be written as : $${K_P} = {\left( {atm} \right)^{\Delta x}}$$
Where $$\Delta x = $$   change in number of moles (difference in number of moles of products $$-$$ reactants).
46
Equilibrium constant of a reaction varies with the
Discuss
Answer & Solution
Answer: Option C
Solution:
The equilibrium constant $$\left( {{K_C}} \right)$$   is dependent only on temperature and nature of reactants and products involved and the relation is given as : $${K_C} = A{e^{ - \frac{{{E_A}}}{{RT}}}}$$
47
Which of the following will increase the volume of a real gas by four times ?
Discuss
Answer & Solution
Answer: Option B
Solution:
According to the gas law we can write $$\frac{{{P_1}{V_1}}}{{{T_1}}} = \frac{{{P_2}{V_2}}}{{{T_2}}}$$
So by reducing the pressure to $$\frac{P}{4}$$ at constant temperature the volume increases to $$4$$ times the initial volume.
48
The accentric factor of a materical, 'ω', is defined as ω = -log10 (Prsat)Tr-1 = 0.7, where, Prsat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always
Discuss
Answer & Solution
Answer: Option B
No explanation is given for this question. Let's Discuss on Board
49
The number of degrees of freedom for a mixture of ice and water (liquid) are
Discuss
Answer & Solution
Answer: Option C
Solution:
Given, number of components $$= 1$$
Number of phases $$= 2$$
So, degree of freedom $$f = 1 - 2 + 2 = 1$$
50
A solute distributes itself between two non-miscible solvents in contact with each other in such a way that, at a constant temperature, the ratio of its concentrations in two layers is constant, irrespective of its total amount". This is
Discuss
Answer & Solution
Answer: Option A
Solution:
The distribution laws says that for two non-miscible solvents will be in equilibrium if the chemical potential of solute is same in both the phases the concentration need not be equal but the ratio of concentrations will be remains constant once equilibrium is reached.