MEDIUM

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State Kelvin-Planck statement of the second law of thermodynamics

Important Questions on Thermodynamics

HARD

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Two ideal Carnot engines operate in a cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures,

T_{1}

and

T_{2}

. The temperature of the hot reservoir of the first engine is

T_{1}

and the temperature of the cold reservoir of the second engine is

T_{2}

T

is the temperature of the sink of the first engine which is also the source for the second engine. How is

T

related to

T_{1}

and

T_{2}

, if both the engines perform an equal amount of work?

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Consider the following liquid - vapour equilibrium.

L i q u i d ⇌ V a p o u r

Which of the following relations is correct?

HARD

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Graphs below show the entropy versus energy $U$ of two systems $1$ and $2$ at constant volume. The initial energies of the systems are indicated by $U_{1, i}$ and $U_{2, i},$ respectively. Graphs are drawn to the same scale. The systems are then brought into thermal contact with each other. Assume that, at all times the combined energy of the two systems remains constant. Choose the most appropriate option indicating the energies of the two systems and the total entropy after they achieve the equilibrium.

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EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

By leaving the door of a small standard domestic refrigerator open, it is not possible to cool a room, because it violates the ______

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Standard entropies of

X_{2}, Y_{2}

and

{XY}_{3}

are

60, 40

and

50 J / K / mol

respectively. At what temperature the following reaction will be at equilibrium

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

The carnot heat engine have an efficiency of

50 % .

The temperature of sink is maintained at

500 K .

To increase the efficiency upto

80 %,

the increment in the source temperature is

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

One mole of an ideal monatomic gas undergoes the following four reversible processes:
Step

1 :

It is first compressed adiabatically from volume

V_{1}

1 m^{2} .

Step

2 :

then expanded isothermally to volume

10 m^{3}

Step

3 :

then expanded adiabatically to volume

V_{3}

Step

4 :

then compressed isothermally to volume

V_{1} .

If the efficiency of the above cycle is

\frac{3}{4}

then

V_{1}

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

A process has

Δ H = 200 J m o l^{- 1}

and

Δ S = 40 J K^{- 1} m o l^{- 1} .

Out of the values given below choose the minimum temperature above which the process will be spontaneous:

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

No process is possible whose sole result is the transfer of heat from a colder object to a hotter object. This is Clausius statement for

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

"Heat cannot be itself flow from a body at lower temperature to a body at higher temperature". This statement corresponds to

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Two solid blocks at temperatures

T_{1}

and

T_{2} (T_{1} < T_{2})

are put in thermal contact for a long time inside an insulated container. Choose the correct statement(s).

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

State the second law of thermodynamics.

HARD

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

One mole of an ideal gas at

300 K

in thermal contact with its surroundings expands isothermally from

1.0 L

2.0 L

against a constant pressure of

3.0 atm

. In this process, the change in entropy of the surroundings

(∆ S_{s u r r})

J K^{- 1}

is:

(1 L atm = 101.3 J)

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

Consider a two stage Carnot engine. In the first stage heat

Q_{1}

is absorbed at temperature

T

and heat

Q_{2}

is expelled at temperature

α T

(where

α < 1

). In the second stage heat

Q_{2}

is absorbed at temperature

α T

and heat

Q_{3}

is expelled at temperature

β T (β < α) .

The efficiency of the Carnot engine will be

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is:

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

The process with negative entropy change is:

HARD

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

The entropy change associated with the conversion of

1 k g

of ice at

273 K

to water vapours at

383 K

is:

(Specific heat of water liquid and water vapour are

4.2 k J K^{-}

and

2.0 k J K^{- 1} k g^{- 1}

; heat of liquid fusion and vaporization of water are

334 k J k g^{- 1}

and

2491 k J k g^{- 1}

, respectively). (

l o g

273 = 2.436, \log 373 = 2.572, \log 383 = 2.583

)

EASY

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

An engine operating between the boiling and freezing points of water will have

A. Efficiency more than $27 %$ .

B. Efficiency less than the efficiency of a Carnot engine operating between the same two temperatures.

C. Efficiency equal to $27 %$ .

D. Efficiency less than $27 %$ .

Choose the correct answer from the options given below

HARD

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

What will be the $Δ H °$ and $Δ S °$ values for the given cell having $E°$ at $20 ° C$ and $30 ° C$ to be $0.18 V$ and $0.28 V$ respectively?

The cell: (Pt) $H_{2} / H^{+} / / KCl / {Hg}_{2} {Cl}_{2} / Hg$ (Given: $1 F = 96500$ Coulombs)

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>Second Law of Thermodynamics

For the following reaction

${Fe}_{2} O_{3 (s)} + 3 {CO}_{(g)} ⟶ 2 {Fe}_{(s)} + 3 {CO}_{2 (g)} ΔH ° = - 29.8 kJ$ and $ΔS ° = 15 {JK}^{- 1}$ . What is the value of ${ΔS}_{(total)}$ at $298 K$ ?

State Kelvin-Planck statement of the second law of thermodynamics

Important Questions on Thermodynamics

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