# 2nd Law Thermodynamics And Entropy Quiz

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The study of the relationships between heat, work, temperature, and energy is known as thermodynamics. The quiz on 2nd law of thermodynamics and entropy is designed to test your knowledge of the subject. The quiz contains questions that will help you solidify your conceptual understanding. Take the quiz and see how well you know heat energy and its conversion into mechanical energy. If you like the quiz, do share it with your friends and family. All the best!

• 1.

### How is it possible that heat can spontaneously go from a cold object to a hot object?

• A.

By having one way super conductive material between them

• B.

Work can be done by the system to make this happen

• C.

Work can be done to the system to make this happen

• D.

Cold objects can never give thermal energy to hot objects

C. Work can be done to the system to make this happen
Explanation
According to the second law of thermodynamics, heat naturally flows from a hot object to a cold object. However, by doing work on the system, it is possible to reverse this natural flow and transfer heat from a cold object to a hot object. This can be achieved by using external energy sources to drive the heat transfer process, such as using a heat pump or a refrigeration system.

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• 2.

### What is Entropy a measurement of?

• A.

Energy of a system

• B.

Change in energy in a chemical reaction

• C.

Temperature

• D.

Average particular energy in a system

• E.

Disorder in a system

E. Disorder in a system
Explanation
Entropy is a measurement of the disorder in a system. It quantifies the randomness or chaos within a system. As entropy increases, the system becomes more disordered, and as entropy decreases, the system becomes more ordered. This concept is widely used in thermodynamics to understand the behavior of energy and matter in various processes.

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• 3.

### What is true about entropy

• A.

If it increases in one place, it MUST decrease elsewhere

• B.

If it decreases in one place, it MUST increase elsewhere

• C.

It must decrease in the universe

• D.

It must stay constant in the universe

B. If it decreases in one place, it MUST increase elsewhere
Explanation
Entropy is a measure of the disorder or randomness in a system. According to the second law of thermodynamics, the total entropy of an isolated system always increases over time. Therefore, if entropy decreases in one place, it must increase elsewhere in order to maintain the overall increase in entropy in the system. This is because the decrease in entropy in one area would result in a corresponding increase in order or organization, which must be compensated by an increase in disorder or randomness somewhere else.

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• 4.

### According to second law of thermodynamics cycle efficiency of thermodynamics must be

• A.

Less than unity

• B.

Greater than unity

• C.

Zero

• D.

None of the above

A. Less than unity
Explanation
The second law of thermodynamics states that heat flows from a higher temperature region to a lower temperature region spontaneously. This implies that not all the heat energy can be converted into work. The cycle efficiency is a measure of how efficiently a thermodynamic cycle converts heat into work. Since some heat energy is always lost in the process, the cycle efficiency will always be less than unity (less than 1). Therefore, the correct answer is "Less than unity".

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• 5.

### External mechanical Irreversibility is shown by which process?

• A.

• B.

Isothermal dissipation of work

• C.

Both of the above

• D.

None of the above

C. Both of the above
Explanation
External mechanical irreversibility is shown by both the adiabatic dissipation of work and the isothermal dissipation of work. In both processes, work is being dissipated irreversibly, meaning it cannot be fully recovered. Adiabatic dissipation of work occurs when work is done on a system without any heat transfer, resulting in an increase in entropy. Isothermal dissipation of work occurs when work is done on a system while maintaining a constant temperature, also leading to an increase in entropy. Both processes involve irreversible dissipation of work, indicating external mechanical irreversibility.

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• 6.

### Chemical dissociation is always?

• A.

Exothermic

• B.

Endothermic

• C.

Reversible

• D.

Endothermic and reversible

A. Exothermic
Explanation
Chemical dissociation refers to the process in which a compound breaks down into its constituent elements or ions. This process usually releases energy in the form of heat, making it exothermic. The energy is released because the bonds between the atoms in the compound are being broken, resulting in a more stable state. Therefore, chemical dissociation is typically exothermic.

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• 7.

### The entropy of water at zero degree celsius is?

• A.

0

• B.

5

• C.

4

• D.

2

A. 0
Explanation
At zero degrees Celsius, water is in its solid state, which is ice. In this state, the water molecules are arranged in a highly ordered and structured pattern. Entropy is a measure of the disorder or randomness in a system. Since the molecules in ice are highly ordered, the entropy of water at zero degrees Celsius is very low, approaching zero. Therefore, the correct answer is 0.

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• 8.

### The largest unit of energy is?

• A.

Calorie

• B.

Joule

• C.

Volt

• D.

Watt

A. Calorie
Explanation
The calorie is the correct answer because it is the largest unit of energy. It is defined as the amount of energy required to raise the temperature of one gram of water by one degree Celsius. The joule, volt, and watt are also units of energy, but they are smaller than the calorie.

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• 9.

### According to Kirchhoff's law, the factor affecting the heat of reaction is?

• A.

Temperature

• B.

Pressure

• C.

Mass

• D.

Volume

A. Temperature
Explanation
According to Kirchhoff's law, the factor affecting the heat of reaction is temperature. This law states that the heat of reaction is directly proportional to the temperature change. As temperature increases, the heat of reaction also increases. This is because temperature affects the kinetic energy of the reactant molecules, leading to more collisions and increased reaction rates. Therefore, temperature plays a crucial role in determining the heat of reaction.

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• 10.

### In a heat engine, what is the relationship between Qh, Qc and W

• A.

W = Qh + Qc

• B.

W = Qc - Qh

• C.

W = Qh - Qc

• D.

Q + Qh, + Qc = 0

C. W = Qh - Qc
Explanation
Qh is turned into work and some heat is ejected
Therefore Qh = W + Qc
Hence w = Qh - Qc

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