# Extractive Metallurgy Questions and Answers – Thermodynamic Equilibrium

This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Thermodynamic Equilibrium”.

1. What is the use of chemical thermodynamics?
a) To predict the feasibility of a reaction
b) To predict the cost per capita of the reaction process
c) To calculate the temperature gradient of the reaction
d) To reduce the energy required by the reaction process

Explanation: Chemical thermodynamics is used to predict the feasibility of a reaction. It also helps in the quantitative calculation of the equilibrium state of a system. These calculations are done in terms of pressure, temperature and composition.

2. Which of the following can be referred to any part of the universe understudy?
a) Surroundings
b) System
c) State of a system
d) Internal energy

Explanation: In thermodynamics, a system is referred to as a part of the universe under study. It consists of a definite amount of substances. It is confined in space by walls known as system boundary.

3. Which of the following system cannot exchange energy or matter with any system?
a) Open system
b) Closed system
c) Isolated system
d) Duplicate system

Explanation: There are three types of system-open, closed and isolated. An open system can exchange energy and matter with its surroundings whereas isolated system cannot exchange energy and matter with any system. A closed system can exchange energy but cannot exchange matter with its surroundings.

4. The part left outside a system in a universe is known as a state of the system.
a) True
b) False

Explanation: The part which is left outside a system in a Universe is known as surroundings. The interaction between the system and surrounding determines the type of system under study. The system and the surrounding is separated by a system boundary.

5. What is the correct formula for the change in internal energy for a system?
a) ΔE = q + w
b) ΔE = w – q
c) ΔE = nRT
d) ΔE = q – w

Explanation: Change in internal energy for a system is equal to the sum of heat energy absorbed by the system and work done on the system. Therefore, ΔE = q – w, is the correct formula for the change in internal energy. ‘W’ is positive when the work is done by the system.

6. An extensive property depends on the amount of matter in a system.
a) True
b) False

Explanation: There are two types of property–extensive and intensive. An extensive property depends on the amount of a substance in a system whereas intensive property is independent of mass. Example of extensive property is volume.

7. Which new function is generated by the formulation of the second law of thermodynamics?
a) Entropy
b) Enthalpy
c) Heat capacity
d) Free energy

Explanation: The second law of thermodynamics develops a concept of new function which is called entropy. It is denoted as ‘S’. It is an extensive property. It helps apply thermodynamics to mechanical processes.

8. Which of the following is the correct formula for entropy?
a) dS = T/dqreversible
b) dS = dqreversible/T
c) dS = Cp.dT
d) dS = Cp/T

Explanation: Entropy is the measure of the thermal energy of a system that is not available for useful work. It is measured using the formula, dS = dqreversible/T = (Cp.dT)/T, where qreversible = heat absorbed during reversible process and Cp = Heat capacity at constant pressure.

9. What does the Hess’s law of constant heat summation state?
a) Heat change of reaction is same when they take place in one step as well as in one or more steps
b) Heat change of a reaction is different when they take place in one step
c) Heat change of a reaction is different when they take place in one or more steps
d) Heat change of reaction is different when they take place in one step as well as in one or more steps

Explanation: Hess’s law of constant heat summation state that the heat change of a reaction is the same, independent of the number of steps which took place. It states that the enthalpy of a reaction is independent of the pathway between the initial and final states. This law shows that enthalpy is a state function.

10. What will happen if a process keeps the entropy of an isolated system constant?
a) The process is not possible
b) Process is possible
c) The process is possible both in forward and backward directions
d) The process will have no effect

Explanation: A process increasing the entropy of an isolated system is possible and decreasing the entropy of the isolated system is impossible. Any process which keeps the entropy of an isolated system constant is possible in both forward and backward directions.

Sanfoundry Global Education & Learning Series – Extractive Metallurgy.

To practice all areas of Extractive Metallurgy, here is complete set of Multiple Choice Questions and Answers.

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