At a certain temperature, T(K), during a process, 500 J is absorbed by the system and work of 200 J is done by the system. Then change in internal energy of the system is :
1. 700 J
2. 300 J
3. 400 J
4. 500 J
Subtopic:  First Law of Thermodynamics |
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Level 2: 60%+
NEET - 2026
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Consider the following reaction:
2A (g) + B (g) → 2D (g)
\(ΔU^⊖\)=−10 \(kJ mol^{−1}\) and \(ΔS^⊖\)=−44 \(J K^{−1}\) at 298 K.

Identify the correct option with \(ΔG^⊖\) for the reaction and spontaneity of the reaction at 298 K.
(Given : R=\(8.31 ~J mol^{−1} K^{−1}\))
1. −1.635 kJ mol−1, spontaneous
2. +0.63568 kJ mol−1, non-spontaneous
3. −0.63568 kJ mol−1, spontaneous
4. +1.635 kJ mol−1, non-spontaneous
Subtopic:  Spontaneity & Entropy | Gibbs Energy Change |
 57%
Level 3: 35%-60%
NEET - 2026
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Two moles of an ideal gas undergo free expansion from 10 L to 100 L at 300 K. The Values of \(\Delta \mathrm{S}_{\text {system }}\) and \(\Delta \mathrm{S}_{\text {surroundings }}\) are :
(R is  universal gas constant)
 
1. \(\Delta \mathrm{S}_{\text {system }}=4.606 \mathrm~{R} ; \Delta \mathrm{S}_{\text {surroundings }}=0\)
2. \(\Delta \mathrm{~S}_{\text {system }}=0 ;~ \Delta \mathrm{S}_{\text {surroundings }}=0 \)
3. \(\Delta \mathrm{~S}_{\text {system }}=4.606~ \mathrm{R} ; \Delta \mathrm{S}_{\text {surroundings }}= -4.606 \mathrm{R}\)
4. \(\Delta \mathrm{~S}_{\text {system }}=0 ; \quad \Delta ~~\mathrm{S}_{\text {surroundings }}= 4.606 \mathrm{R}\)
Subtopic:  Spontaneity & Entropy |
Level 4: Below 35%
NEET - 2026
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Consider the reversible processes for 1.0 mol of an ideal gas as shown in the figure.

w₁, w₂, w₃ and w₄ represent work done (in calories) in the processes 1, 2, 3 and 4, respectively; ΔU₂ and ΔU₄ are changes in the internal energy for the processes 2 and 4, respectively. [use R = 2 cal K⁻¹ mol⁻¹]
The correct option is:
 
1. w₁ + w₂ + w₃ + w₄ = 0
2. w₁ + w₃ = -2T₁ ln \(\frac{V₂}{V₁}\) - 2T₂ ln \(\frac{V₄}{V₃}\)
3. w₂ + w₄ = ΔU₂ - ΔU₄
4. w₁ + w₂ = 2T₁ ln \(\frac{V₂}{V₁}\)
Subtopic:  Thermodynamics' Properties and process |
 51%
Level 3: 35%-60%
NEET - 2026
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The standard heat of formation, in kcal/mol of \(Ba^{2+}\) is :
[Given : standard heat of formation of \(SO^{2-}_4\) ion (aq) \(= -216~ \text{kcal/mol}\), standard heat of crystallisation of \(BaSO_4 (s)= -4.5~\text{ kcal/mol,}\) standard heat of formation of \(BaSO_4 (s)= -349 ~\text{kcal/mol]}\)
1. \(+133.0 \) 2. \(+220.5\)
3. \(-128.5 \) 4. \(-133.0\)
Subtopic:  Thermochemistry |
Level 3: 35%-60%
NEET - 2025
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Match List I with List II.
List-I (Process) List-II (Conditions)
A. Isothermal process I. No heat exchange
B. Isochoric process II. Carried out at constant temperature
C. Isobaric process III. Carried out at constant volume
D. Adiabatic process IV. Carried out at constant pressure
Choose the correct answer from the options given below:
1. \(\text { A-IV, B-II, C-III, D-I }\) 2. \(\text { A-I, B-II, C-III, D-IV }\)
3. \(\text { A-II, B-III, C-IV, D-I }\) 4. \(\text { A-IV, B-III, C-II, D-I }\)
Subtopic:  Thermodynamics' Properties and process |
 86%
Level 1: 80%+
NEET - 2024
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In which of the following processes entropy increases?
A. A liquid evaporates to vapour.
B. Temperature of a crystalline solid lowered from \(130~\text{K}\) to \(0~\text{K}.\)
C. \(2 \mathrm{NaHCO}_{3(\mathrm{~s})} \rightarrow \mathrm{Na}_2 \mathrm{CO}_{3(\mathrm{~s})}+\mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}\)
D. \(\mathrm{Cl}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{Cl}_{(\mathrm{g})}\)
Choose the correct answer from the options given below:
1. \(\text { A, B and D }\) 2. \(\text { A, C and D }\)
3. \(\text { C and D }\) 4. \(\text { A and C }\)
Subtopic:  Spontaneity & Entropy |
 73%
Level 2: 60%+
NEET - 2024
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Work done during reversible isothermal expansion of one mole of hydrogen gas at 25°C from a pressure of 20 atmospheres to a pressure of 10 atmospheres is:
(Given: R = 2.0 cal K–1 mol–1)
1. –413.14 calories 2. 413.14 calories 
3. 100 calories 4. 0 calorie
Subtopic:  First Law of Thermodynamics |
 70%
Level 2: 60%+
NEET - 2024
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Enthalpy of combustion of carbon to carbon dioxide is \(-390.0~\text{kJ mol}^{-1}.\) The amount of heat released when \(35.0~\text{g}\) of \(\mathrm{CO_2}\) is formed from the reaction of carbon and dioxygen gas, is:
1. \(310~\text{kJ}\) 2. \(490~\text{kJ}\)
3. \(245~\text{kJ}\) 4. \(700~\text{kJ}\)
Subtopic:  Enthalpy & Internal energy |
 74%
Level 2: 60%+
NEET - 2024
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Choose the correct statement for the work done in the expansion and heat absorbed or released when 5 liters of an ideal gas at 10 atmospheric pressure isothermally expands into a vacuum until the volume is 15 liters:
1. Both the heat and work done will be greater than zero.
2. Heat absorbed will be less than zero and work done will be positive.
3. Work done will be zero and heat absorbed or evolved will also be zero.
4. Work done will be greater than zero and heat absorbed will remain zero.
Subtopic:  First Law of Thermodynamics |
 62%
Level 2: 60%+
NEET - 2024
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