For the reaction, 2Cl(g)  Cl2(g), the correct option is:
1. \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) 2. \(\Delta_{\mathrm{r}} \mathrm{H}<0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0 \)
3. \(\Delta_{\mathrm{r}} \mathrm{H}<0 \) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) 4. \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0\)

Subtopic:  Enthalpy & Internal energy | Spontaneity & Entropy |
 61%
Level 2: 60%+
NEET - 2020
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The correct option for free expansion of an ideal gas under adiabatic condition is:

1.  q=0, T<0 and w>0

2.  q<0, T=0 and w=0

3.  q>0, T>0 and w>0

4.  q=0, T=0 and w=0

Subtopic:  2nd & 3rd Law of Thermodynamics |
 76%
Level 2: 60%+
NEET - 2020
Hints

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%
Level 1: 80%+
NEET - 2020
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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 |
 70%
Level 2: 60%+
NEET - 2020
Hints

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 |
 57%
Level 3: 35%-60%
NEET - 2020
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Reversible expansion of an ideal gas under isothermal and adiabatic conditions are shown in the figure:

ABIsothermal expansion

ACAdiabatic expansion

Which of the following options is not correct?

1. \(\Delta S_{\text {isothermal }}>\Delta S_{\text {adiabatic }} \) 2. \(T_A=T_B \)
3. \(W_{\text {isothermal }}>W_{\text {adiabatic }} \) 4. \(T_C>T_A\)
Subtopic:  2nd & 3rd Law of Thermodynamics |
 55%
Level 3: 35%-60%
NEET - 2019
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What is the amount of work done by an ideal gas, if the gas expands isothermally from \(10^{-3}~m^3\) to \(10^{-2}~m^3\) at \(300~K\)against a constant pressure of \(10^{5}~Nm^{-2}\)?

1. \(+270 ~kJ\) 2. \(–900 ~J\)
3. \(+900 ~kJ\) 4. \(–900~ kJ\)
Subtopic:  First Law of Thermodynamics |
 72%
Level 2: 60%+
NEET - 2019
Hints

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 |
 76%
Level 2: 60%+
AIPMT - 2011
Hints

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 |
 80%
Level 1: 80%+
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 |
 92%
Level 1: 80%+
AIPMT - 2010
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