At standard conditions, if the change in the enthalpy for the following reaction is -109 kJ mol-1
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 |
 53%
From NCERT
NEET - 2020
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Consider the following processes:

                                       ∆H (kJ/mol)
½ A → B                            + 150
3B → 2C + D                      –125
E + A → 2D                        +350

For B + D → E + 2C, ∆H will be-

1. 325 kJ/mol 

2. 525 kJ/mol

3. –175 kJ.mol 

4. –325 kJ/mol

Subtopic:  Enthalpy & Internal energy |
 72%
From NCERT
AIPMT - 2011
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For vaporization of water at 1 atmospheric pressure, the values of ∆H and ∆S are 40.63 kJ mol–1 and 108.8 JK–1 mol–1, respectively. The temperature when Gibbs energy change (∆G) for this transformation will be zero, is:

1. 393.4 K

2. 373.4 K

3. 293.4 K

4. 273.4 K

Subtopic:  Gibbs Energy Change |
 78%
From NCERT
AIPMT - 2010
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Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be:

1. 3 Joules

2. 9 Joules

3. Zero

4. Infinite

Subtopic:  First Law of Thermodynamics |
 90%
From NCERT
AIPMT - 2010
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The following two reactions are knownFe2O3(s)+3CO(g)2Fe(s)+3CO2(g);
H=-26.88 kJ
FeO(s)+CO(g)Fe(s)+CO2(g);
H=-16.5 kJ

The value of H for the following reaction

Fe2O3(s)+CO(g)2FeO(s)+CO2(g) is:

1. -43.3 kJ

2. -10.3 kJ

3. +6.2 kJ

4. +10.3 kJ

Subtopic:  Enthalpy & Internal energy |
 76%
From NCERT
AIPMT - 2010
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Match List – I (Equations) with List – II (Type of processes) and select the correct option.

List – I List – II
Equation  Type of processes
(a) Kp > Q  (i) Non-spontaneous
(b) ∆Gº < RT ln Q  (ii) Equilibrium
(c) Kp = Q  (iii) Spontaneous and endothermic
(d) T > \(\frac{\Delta H}{\Delta S}\) (iv) Spontaneous
 
Options: (a) (b) (c) (d)
1. (iii) (iv) (ii) (i)
2. (iv) (i) (ii) (iii)
3. (ii) (i) (iv) (iii)
4. (i) (ii) (iii) (iv)
Subtopic:  Spontaneity & Entropy | Gibbs Energy Change |
 63%
From NCERT
AIPMT - 2010
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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 |
 69%
From NCERT
NEET - 2020
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A reaction occurs spontaneously if:

1. T∆S > ∆H and ∆H is +ve and ∆S are –ve

2. T∆S = ∆H and both ∆H and ∆S are +ve

3. T∆S < ∆H and both ∆H and ∆S are +ve

4. T∆S > ∆H and both ∆H and ∆S are +ve

Subtopic:  Spontaneity & Entropy |
 76%
From NCERT
AIPMT - 2005
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Which of the following pairs of chemical reactions is certain to result in a spontaneous reaction:

1. Endothermic and decreasing disorder

2. Exothermic and increasing disorder

3. Endothermic and increasing disorder

4. Exothermic and decreasing disorder

Subtopic:  Spontaneity & Entropy |
 76%
From NCERT
AIPMT - 2005
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Identify the correct statement regarding entropy:

1. At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero
2. At absolute zero of temperature, the entropy of a perfectly crystalline substance is +ve
3. At absolute zero of temperature, the entropy of a perfectly crystalline substance is taken to be zero
4. At 0 °C , the entropy of a perfectly crystalline substance is taken to be zero
Subtopic:  2nd & 3rd Law of Thermodynamics |
 64%
From NCERT
AIPMT - 1998
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