A process among the following shows decrease in entropy is :

1. \(2 \text H \left(g\right)\rightarrow\text H_{2} \left(g\right)\)

2. Evaporation of water

3. Expansion of a gas at a constant temperature

4. Sublimation of solid to gas

Subtopic:  Gibbs Energy Change |
 82%
Level 1: 80%+
NEET - 2019
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Under the isothermal condition, a gas at \(300 \mathrm{~K}\) expands from \(0.1 \mathrm{~L}\) to \(0.25 \mathrm{~L}\) against a constant external pressure of 2 bar. The work done by the gas is:

1. \(30 ~\mathrm {J} \) 2. \(-30 ~\mathrm{J} \)
3. \(5~ \mathrm{kJ}\) 4. \(25~ \mathrm{J}\)
Subtopic:  2nd & 3rd Law of Thermodynamics |
 81%
Level 1: 80%+
NEET - 2019
Hints

What is the amount of work done by an ideal gas, if the gas expands isothermally from \(10^{-3}~m^3\) to \(10^{-2}~m^3\) at \(300~K\)against a constant pressure of \(10^{5}~Nm^{-2}\)?

1. \(+270 ~kJ\) 2. \(–900 ~J\)
3. \(+900 ~kJ\) 4. \(–900~ kJ\)
Subtopic:  First Law of Thermodynamics |
 72%
Level 2: 60%+
NEET - 2019
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Reversible expansion of an ideal gas under isothermal and adiabatic conditions are shown in the figure:

ABIsothermal expansion

ACAdiabatic expansion

Which of the following options is not correct?

1. \(\Delta S_{\text {isothermal }}>\Delta S_{\text {adiabatic }} \) 2. \(T_A=T_B \)
3. \(W_{\text {isothermal }}>W_{\text {adiabatic }} \) 4. \(T_C>T_A\)
Subtopic:  2nd & 3rd Law of Thermodynamics |
 55%
Level 3: 35%-60%
NEET - 2019
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Hydrolysis of sucrose is given by the following reaction

Sucrose + H2 Glucose + Fructose

If the equilibrium constant (Kc) is 2×1013 at 300 K, the value of rG at the same temperature will be:

1. 8.314 J mol–1 K–1×300 K×ln (2×1013)

2. 8.314 J mol–1 K–1×300 K×ln (3×1013)

3. –8.314 J mol–1 K–1×300 K×ln (4×1013)

4. –8.314 J mol–1 K–1×300 K×ln (2×1013)

Subtopic:  Gibbs Energy Change |
 80%
Level 1: 80%+
NEET - 2020
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For the reaction, 2Cl(g)  Cl2(g), the correct option is:
1. \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) 2. \(\Delta_{\mathrm{r}} \mathrm{H}<0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0 \)
3. \(\Delta_{\mathrm{r}} \mathrm{H}<0 \) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) 4. \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0\)
Subtopic:  Enthalpy & Internal energy | Spontaneity & Entropy |
 61%
Level 2: 60%+
NEET - 2020
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The correct option for free expansion of an ideal gas under adiabatic condition is:

1.  q=0, T<0 and w>0

2.  q<0, T=0 and w=0

3.  q>0, T>0 and w>0

4.  q=0, T=0 and w=0

Subtopic:  2nd & 3rd Law of Thermodynamics |
 76%
Level 2: 60%+
NEET - 2020
Hints

If for a certain reaction rH is 30 kJ mol–1 at 450 K, the value of rS (in JK–1 mol–1) for which the same reaction will be spontaneous at the same temperature is:

1. 70 2. –33
3. 33 4. –70
Subtopic:  Spontaneity & Entropy |
 70%
Level 2: 60%+
NEET - 2020
Hints

At standard conditions, if the change in the enthalpy for the following reaction is –109 kJ mol
H2(g)+Br2(g)2HBr(g) and the bond energy of H2 and Br2 is 435 kJ mol–1 and 192 kJ mol–1 respectively, what is the bond energy (in kJ mol–1) of HBr?

1. 368 2. 736
3. 518 4. 259
Subtopic:  Thermochemistry |
 57%
Level 3: 35%-60%
NEET - 2020
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Which of the following options correctly represents the relationship between \(C_p \text { and } C_V\) for one mole of an ideal gas?

1. \(C_P=R C_V \) 2. \(C_V=RC_P \)
3. \(C_P+C_V=R \) 4. \(C_{{P}}-{C}_{{V}}={R}\)
Subtopic:  Cp & Cv |
 88%
Level 1: 80%+
NEET - 2021
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