Given the following reaction:

N2H4(g)N2H2(g)+H2(g);

[Given:  ∆ H= 109 kJ/mol, B.E. of (N-N) = 163 kJ/mol, B.E. of (N-H) = 391 kJ/mol and B.E. of (H-H) = 436 kJ/mol]

Calculate the bond enthalpy of N = N:

1. 182 kJ/mol

2. 400 kJ/mol

3. 300 kJ/mol

4. 218 kJ/mol

Subtopic:  Thermochemistry |
 73%
Level 2: 60%+
Hints

The pair of isochoric among the transformation of state is:

1. K to L and L to M

2. L to M and N to K

3. L to M and M to N

4. M to N and N to K

Subtopic:  Classification of System, Extensive & Intensive Properties |
 88%
Level 1: 80%+
Hints

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
Hints

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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

Thermodynamics is not concerned about:

1. Energy changes involved in a chemical reaction.
2. The extent to which a chemical reaction proceeds.
3. The rate at which a reaction proceeds.
4. The feasibility of a chemical reaction.
Subtopic:  Thermodynamics' Properties and process |
 73%
Level 2: 60%+
Hints

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 |
 77%
Level 2: 60%+
AIPMT - 2007
Hints

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The heat of combustion of carbon to CO2 is –393.5 KJ/mol. The heat released upon the formation of 35.2 g of CO2 from carbon and oxygen gas is:

1. –315 KJ 2. +315 KJ
3. –630 KJ 4. +630 KJ
Subtopic:  Thermochemistry |
 75%
Level 2: 60%+
NEET - 2015
Hints

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

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 positive.
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 |
 70%
Level 2: 60%+
AIPMT - 1998
Hints

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Following reaction occurs at 25C :

2NO(g) , (1 × 10-5   atm) + Cl2(g), ( 1×10-2 atm) ⇌ 2NOCl(g), ( 1×10- 2 atm) ∆Go   is-

1. -45.65 kJ

2. -28.53 kJ

3. -22.82 kJ

4. -57.06 kJ

Subtopic:  Gibbs Energy Change |
 61%
Level 2: 60%+
Hints