Under the isothermal condition, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is:
[Given that 1 L bar = 100 J]

1. 30 J

2. -30 J

3. 5 kJ

4. 25 J

Subtopic:  2nd & 3rd Law of Thermodynamics |
 78%
From NCERT
NEET - 2019
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A process among the following shows decrease in entropy is :

1. 2H(g) H2(g)

2. Evaporation of water

3. Expansion of a gas at a constant temperature

4. Sublimation of solid to gas

Subtopic:  Gibbs Energy Change |
 79%
From NCERT
NEET - 2019
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The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexane (C6H12) are -241, -3800 and -3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is:

1. -121 kJ per mol

2. +121 kJ per mol

3. +242 kJ per mol

4. -242 kJ per mol

Subtopic:  Thermochemistry |
 56%
From NCERT
AIPMT - 2006
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The enthalpy and entropy change for the reaction: Br2 (l) + Cl2 (g) →2BrCl(g), are 30kJ mol-1 and 105 JK-1 mol-1 respectively. The temperature at which the reaction will be in equilibrium is: 

1. 285.7 K

2. 273 K

3. 450 K

4. 300 K

Subtopic:  Gibbs Energy Change |
 72%
From NCERT
AIPMT - 2006
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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 |
 80%
From NCERT
AIPMT - 2006
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Identify the correct statement for change of Gibbs energy for a system (ΔGsystem) at constant temperature and pressure:

1. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) > 0 , the process is spontaneous
2. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) = 0 , the system has attained equilibrium
3. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) = 0 , the system is still moving in a particular
direction.
4. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\)< 0 , the process is not spontaneous

Subtopic:  Gibbs Energy Change |
 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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The bond energy of H—H and Cl-Cl is 430 kJ mol-1 and 240 kJ mol-1 respectively
and ΔHf for HCl is -90 kJ mol-1. The bond enthalpy of HCl is:

1. 290 kJ mol-1

2. 380 kJ mol-1

3. 425 kJ mol-1

4. 245 kJ mol-1

Subtopic:  Thermochemistry |
 60%
From NCERT
AIPMT - 2007
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Consider the following reactions: 

(i) H+(aq) + OH-(aq) → H2O(l)
ΔH = -x1 kJmol-1
(ii) H2(g) + 1/2O2(g) → H2O(l)
ΔH = -x2 kJmol-1
(iii) CO2(g) + H2(g) → CO (g) + H2O(l)
ΔH = -x3 kJmol-1
(iv) C2H2(g) + 5/2O2(g) →  2CO+ H2O(l)
ΔH = -x4 kJmol-1


Enthalpy of formation of H2O(l) is :

1. -x3 kJ mol-1

2. -x4 kJ mol-1

3. -x1 kJ mol-1

4. -x2 kJ mol-1

Subtopic:  Thermochemistry |
 75%
From NCERT
AIPMT - 2007
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Bond dissociation enthalpy of H2, Cl2, and HCl are 434, 242, and 431 kJ mol1 respectively. Enthalpy of formation of HCl is:

1. 93 kJ mol-1
2. - 245 kJ mol-1
3. -93 kJ mol-1
4. 245 kJ mol-1

Subtopic:  Thermochemistry |
 64%
From NCERT
AIPMT - 2008
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