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%
From NCERT
NEET - 2020
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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 |
 56%
From NCERT
NEET - 2020
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For the reaction, 2Cl(g)  Cl2(g), the correct option is:

1. rH>0 and rS<0

2. rH<0 and rS>0

3. rH<0 and rS<0

4. rH>0 and rS>0

Subtopic:  Enthalpy & Internal energy | Spontaneity & Entropy |
 61%
From NCERT
NEET - 2020
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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%
From NCERT
NEET - 2020
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Reversible expansion of an ideal gas under isothermal and adiabatic conditions are as shown in the figure:

 

ABIsothermal expansion

ACAdiabatic expansion

Which of the following options is not correct?

1. Sisothermal>Sadiabatic

2. TA=TB

3. Wisothermal>Wadiabatic

4. TC>TA

Subtopic:  2nd & 3rd Law of Thermodynamics |
 55%
From NCERT
NEET - 2019
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An ideal gas expands isothermally from 10-3m3 to 10-2 m3 at 300 K against a constant pressure of 105 Nm-2. The work done by  the gas is:

1. +270 kJ 2. –900 J
3. +900 kJ 4. –900 kJ
Subtopic:  First Law of Thermodynamics |
 72%
From NCERT
NEET - 2019
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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 |
 81%
From NCERT
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 |
 80%
From NCERT
NEET - 2019
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Assuming each reaction is carried out in an open container,
Reaction that shows ΔH=ΔE is :

1. H2(g)+Br2(g)2HBr(g)

2. C(s)+2H2O(g)2H2(g)+CO2(g)

3. PCl5(g)PCl3(g)+Cl2(g)

4. 2COg+O2g2CO2g

Subtopic:  Thermodynamics' Properties and process |
 81%
From NCERT
AIPMT - 2006
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Which of the following statements about the advantage of roasting sulphide ore before reduction is not true?
 
1. Carbon and hydrogen act as suitable reducing agents for metal sulphides
2. The \(\Delta_f G^0\) of the sulphide is greater than those for \(C S_2\) and \(\mathrm{H}_2 \mathrm{~S}\)
3. The \(\Delta_f G^0\) is negative for roasting of sulphur ore to oxide.
4. Roasting of the sulphide to the oxide is thermodynamically feasible
Subtopic:  Gibbs Energy Change | Hess's Law |
From NCERT
AIPMT - 2007
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