Thermodynamics Set-1

Question 1

A system that can exchange both matter and energy with the surroundings is known as:

Accepted Answer

Open system

Answer

Closed system

Answer

Isolated system

Answer

Adiabatic system

Question 2

Which of the following is an intensive property?

Accepted Answer

Temperature

Answer

Mass

Answer

Volume

Answer

Enthalpy

Question 3

For an adiabatic process, which of the following is correct?

Accepted Answer

$q = 0$

Answer

$\Delta T = 0$

Answer

$w = 0$

Answer

$\Delta V = 0$

Question 4

The mathematical expression for the First Law of Thermodynamics is:

Accepted Answer

$\Delta U = q + w$

Answer

$\Delta U = q - w$

Answer

$q = \Delta U + w$

Answer

$\Delta H = \Delta U + PV$

Question 5

Which of the following is a state function?

Accepted Answer

Enthalpy

Answer

Heat

Answer

Work

Answer

Heat capacity

Question 6

In an isothermal expansion of an ideal gas into a vacuum (free expansion), the work done is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Maximum

Question 7

The relation between enthalpy change ($\Delta H$) and internal energy change ($\Delta U$) for a reaction involving gases is:

Accepted Answer

$\Delta H = \Delta U + \Delta n_g RT$

Answer

$\Delta U = \Delta H + \Delta n_g RT$

Answer

$\Delta H = \Delta U - \Delta n_g RT$

Answer

$\Delta H = \Delta U + P\Delta V$

Question 8

For the reaction $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$, the value of $\Delta n_g$ is:

Accepted Answer

-2

Answer

2

Answer

4

Answer

-4

Question 9

An endothermic reaction is one in which:

Accepted Answer

Heat is absorbed

Answer

Heat is evolved

Answer

Temperature increases

Answer

Enthalpy decreases

Question 10

The enthalpy of all elements in their standard states at 298 K and 1 bar pressure is:

Accepted Answer

Zero

Answer

Unity

Answer

Less than zero

Answer

Different for each element

Question 11

Which law states that the total enthalpy change for a reaction is the same whether it occurs in one step or multiple steps?

Accepted Answer

Hess’s Law

Answer

Le Chatelier's Principle

Answer

Joule-Thomson Effect

Answer

First Law of Thermodynamics

Question 12

For a process to be spontaneous at all temperatures, the conditions must be:

Accepted Answer

$\Delta H < 0$ and $\Delta S > 0$

Answer

$\Delta H > 0$ and $\Delta S < 0$

Answer

$\Delta H < 0$ and $\Delta S < 0$

Answer

$\Delta H > 0$ and $\Delta S > 0$

Question 13

The measure of randomness or disorder in a system is called:

Accepted Answer

Entropy

Answer

Enthalpy

Answer

Internal Energy

Answer

Gibbs Energy

Question 14

For the process of sublimation of iodine, the sign of $\Delta S$ is:

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Unpredictable

Question 15

The criteria for equilibrium at constant temperature and pressure is:

Accepted Answer

$\Delta G = 0$

Answer

$\Delta G > 0$

Answer

$\Delta G < 0$

Answer

$\Delta S = 0$

Question 16

Which of the following has the highest entropy per mole?

Accepted Answer

$H_2O(g)$ at 373 K

Answer

$H_2O(s)$ at 273 K

Answer

$H_2O(l)$ at 298 K

Answer

$H_2O(l)$ at 373 K

Question 17

The unit of molar heat capacity is:

Accepted Answer

$J mol^{-1} K^{-1}$

Answer

$J K^{-1}$

Answer

$J g^{-1} K^{-1}$

Answer

$kJ mol^{-1}$

Question 18

In an exothermic reaction, the enthalpy of products ($H_p$) and reactants ($H_r$) are related as:

Accepted Answer

$H_p < H_r$

Answer

$H_p > H_r$

Answer

$H_p = H_r$

Answer

$H_p + H_r = 0$

Question 19

Bond dissociation enthalpy is always:

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

May be positive or negative

Question 20

The heat change at constant volume is equal to:

Accepted Answer

$\Delta U$

Answer

$\Delta H$

Answer

$\Delta S$

Answer

$w$

Question 21

Calculate the work done when 2 moles of an ideal gas expand isothermally and reversibly from 10 L to 20 L at 300 K. ($R = 8.314 J mol^{-1} K^{-1}$)

Accepted Answer

$-3457 J$

Answer

$-1728 J$

Answer

$-5227 J$

Answer

$-2303 J$

Question 22

For the reaction $C(s) + O_2(g) \rightarrow CO_2(g)$, which is true?

Accepted Answer

$\Delta H = \Delta U$

Answer

$\Delta H > \Delta U$

Answer

$\Delta H < \Delta U$

Answer

$\Delta H = \Delta U + RT$

Question 23

A reaction is non-spontaneous at all temperatures if:

Accepted Answer

$\Delta H > 0, \Delta S < 0$

Answer

$\Delta H > 0, \Delta S > 0$

Answer

$\Delta H < 0, \Delta S < 0$

Answer

$\Delta H < 0, \Delta S > 0$

Question 24

The entropy of a perfectly crystalline substance at absolute zero is:

Accepted Answer

Zero

Answer

Maximum

Answer

Infinite

Answer

Negative

Question 25

In a bomb calorimeter, the heat measured is:

Accepted Answer

$q_v$

Answer

$q_p$

Answer

$\Delta H$

Answer

$\Delta G$

Question 26

For the process $H_2O(l) \rightarrow H_2O(s)$ at 273 K and 1 atm:

Accepted Answer

$\Delta H = T\Delta S$

Answer

$\Delta H < T\Delta S$

Answer

$\Delta H > T\Delta S$

Answer

$\Delta G < 0$

Question 27

Which of the following describes an isolated system?

Accepted Answer

Water in a sealed thermos flask

Answer

A cup of hot coffee in a room

Answer

Boiling water in an open beaker

Answer

A sealed glass bottle of soda

Question 28

If a gas absorbs 500 J of heat and does 200 J of work, the change in internal energy is:

Accepted Answer

300 J

Answer

700 J

Answer

-300 J

Answer

500 J

Question 29

Standard enthalpy of combustion is always:

Accepted Answer

Negative

Answer

Positive

Answer

Zero

Answer

Temperature dependent only

Question 30

The spontaneous flow of heat always occurs:

Accepted Answer

From high to low temperature

Answer

From low to high temperature

Answer

Without any temperature difference

Answer

Only in a vacuum

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Thermodynamics Set-1

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