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

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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A process among the following shows decrease in entropy is :

1. \(2 \text H \left(g\right)\rightarrow\text H_{2} \left(g\right)\)

2. Evaporation of water

3. Expansion of a gas at a constant temperature

4. Sublimation of solid to gas

Subtopic:  Gibbs Energy Change |
 82%
Level 1: 80%+
NEET - 2019
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Under the isothermal condition, a gas at \(300 \mathrm{~K}\) expands from \(0.1 \mathrm{~L}\) to \(0.25 \mathrm{~L}\) against a constant external pressure of 2 bar. The work done by the gas is:

1. \(30 ~\mathrm {J} \) 2. \(-30 ~\mathrm{J} \)
3. \(5~ \mathrm{kJ}\) 4. \(25~ \mathrm{J}\)
Subtopic:  2nd & 3rd Law of Thermodynamics |
 81%
Level 1: 80%+
NEET - 2019
Hints

The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexane (C6H12) are -241, -3800 and -3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is:

1. -121 kJ per mol

2. +121 kJ per mol

3. +242 kJ per mol

4. -242 kJ per mol

Subtopic:  Thermochemistry |
 59%
Level 3: 35%-60%
AIPMT - 2006
Hints

The enthalpy and entropy change for the reaction: Br2 (l) + Cl2 (g) →2BrCl(g), are 30kJ mol-1 and 105 JK-1 mol-1 respectively. The temperature at which the reaction will be in equilibrium is: 

1. 285.7 K

2. 273 K

3. 450 K

4. 300 K

Subtopic:  Gibbs Energy Change |
 74%
Level 2: 60%+
AIPMT - 2006
Hints

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Assuming each reaction is carried out in an open container,
Reaction that shows ΔH=ΔE is :

1. H2(g)+Br2(g)2HBr(g)

2. C(s)+2H2O(g)2H2(g)+CO2(g)

3. PCl5(g)PCl3(g)+Cl2(g)

4. 2COg+O2g2CO2g

Subtopic:  Thermodynamics' Properties and process |
 82%
Level 1: 80%+
AIPMT - 2006
Hints

Identify the correct statement for change of Gibbs energy for a system (ΔGsystem) at constant temperature and pressure:

1. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) > 0 , the process is spontaneous
2. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) = 0 , the system has attained equilibrium
3. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\) = 0 , the system is still moving in a particular
direction.
4. If \(\begin{equation} \Delta G_{\text {system }} \end{equation}\)< 0 , the process is not spontaneous

Subtopic:  Gibbs Energy Change |
 82%
Level 1: 80%+
AIPMT - 2006
Hints

The bond energy of H—H and Cl-Cl is 430 kJ
mol-1 and 240 kJ mol-1 respectively and ΔHf for HCl is -90 kJ mol-1. The bond enthalpy of HCl is:

1. 290 kJ mol-1

2. 380 kJ mol-1

3. 425 kJ mol-1

4. 245 kJ mol-1

Subtopic:  Thermochemistry |
 63%
Level 2: 60%+
AIPMT - 2007
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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