The bond dissociation energies of X2 , Y2 and XY are in the ratio of 1 : 0.5 : 1. ∆H for the formation of XY is –200 kJ mol–1. The bond dissociation energy of X2 will be

1. 200 kJ mol–1
2. 100 kJ mol–1
3. 800 kJ mol–1
4. 400 kJ mol–1

Subtopic:  Thermochemistry |
From NCERT
NEET - 2018
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Hints

For a given reaction, H =35.5 kJ mol-1 and S = 83.6JK-1 mol-1. The reaction is spontaneous at:
(Assume that H and S do not vary with temperature)

1. T < 425 K 2. T > 425 K
3. All temperatures 4. T > 298 K
Subtopic:  Gibbs Energy Change |
 73%
From NCERT
NEET - 2017
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Hints
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A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy U of the gas in joules will be

(1) 1136.25 J

(2) - 500 J

(3) - 505 J

(4) + 515 J

Subtopic:  First Law of Thermodynamics |
 64%
From NCERT
NEET - 2017
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Hints
To view explanation, please take trial in the course.
NEET 2021 - Achiever Batch - Aryan Raj Singh

For a given reaction, ∆H = 35.5 kJ mol-1 and ∆S = 83.6 J K-1 mol-1 . The reaction is spontaneous at:
(Assume that ∆H and ∆S  do not vary with temperature)

1. T > 425K
2. All temperatures
3. T > 298K
4. T<425K

Subtopic:  Gibbs Energy Change |
 75%
From NCERT
NEET - 2017
To view explanation, please take trial in the course.
NEET 2021 - Achiever Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2021 - Achiever Batch - Aryan Raj Singh

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5atm from an initial volume of 2.50 L to a final volume of 4.50L. The change in internal energy U of the gas in joules will be:
1. -500J
2. -505J
3. -506J
4. -508J

Subtopic:  First Law of Thermodynamics |
From NCERT
NEET - 2017
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Hints
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The correct thermodynamic conditions for the spontaneous reaction at all temperatures is

(a) H>0 and S<0
(b) H<0 and S>0
(c) H<0 and S<0
(d) H<0 and S=0

Subtopic:  Gibbs Energy Change |
 79%
From NCERT
NEET - 2016
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Hints

For a sample of a perfect gas when its pressure is changed isothermally from Pi to Pf, the entropy change is given by:

1. s=nR In pfpi

2. s=nR In pipf

3. s=nRT In pfpi

4. s=RT In pipf

Subtopic:  Spontaneity & Entropy |
 70%
From NCERT
NEET - 2016
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Hints

The correct thermodynamic conditions for a spontaneous reaction at all temperatures is:
1. H > 0 and S< 0
2. H < 0 and S> 0
3. H < 0 and S< 0
4. H > 0 and S = 0
Subtopic:  Gibbs Energy Change |
 82%
From NCERT
NEET - 2016
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NEET 2021 - Achiever Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2021 - Achiever Batch - Aryan Raj Singh