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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NEET 2023 - Target Batch - Aryan Raj Singh
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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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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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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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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 standard free energies of formation(in kJ/mol) at 298 K are -237.2, -394.4, and -8.2 for H2O(l), CO2(g), and pentane (g), respectively. The value of Ecell for the pentane-oxygen fuel cell is:

1. 1.968 V
2. 2.0968 V
3. 1.0968 V
4. 0.0968 V

Subtopic:  Gibbs Energy Change |
 55%
From NCERT
AIPMT - 2008
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NEET 2023 - Target Batch - Aryan Raj Singh
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For the gas phase reaction, 
 PCl5(g)PCl3(g)+Cl2(g)
which of the following conditions is correct?

1. ΔH = 0 and ΔS < 0

2. ΔH > 0 and ΔS > 0

3. ΔH < 0 and ΔS < 0

4. ΔH > 0 and ΔS < 0

Subtopic:  Gibbs Energy Change |
 80%
From NCERT
AIPMT - 2008
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NEET 2023 - Target Batch - Aryan Raj Singh
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The values of ΔH and ΔS for the given reaction are 170 kJ and 170 JK-1, respectively.
C(graphite) + CO2(g)→2CO(g) 
This reaction will be spontaneous at:

1. 710 K
2. 910 K
3. 1110 K
4. 510 K

Subtopic:  Gibbs Energy Change |
 88%
From NCERT
AIPMT - 2009
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From the following bond energies:
H—H bond energy: 431.37 kJ mol-1 
C=C bond energy: 606.10 kJ mol-1 
C—C bond energy: 336.49 kJ mol-1 
C—H bond energy: 410.50 kJ mol-1 
Enthalpy for the reaction, 

will be:

1. 1523.6 kJ mol-1 2. -243.6 kJ mol-1
3. -120.0 kJ mol-1 4. 553.0 kJ mol-1
Subtopic:  Thermochemistry |
 75%
From NCERT
AIPMT - 2009
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NEET 2023 - Target Batch - Aryan Raj Singh
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