Thermodynamics PYQs

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)

C(s) + 2H₂(g) → CH₄(g); ΔH = -74.8 kJ mol⁻¹ Which of the following diagrams gives an accurate representation of the above reaction? [R → reactants, P → products]

The standard heat of formation, in kcal/mol, of $\mathrm{Ba^{2+}}$ is: Given: Standard heat of formation of $\mathrm{SO_4^{2-}(aq)} = -216\ \text{kcal/mol}$ Standard heat of crystallisation of $\mathrm{BaSO_4(s)} = -4.5\ \text{kcal/mol}$ Standard heat of formation of $\mathrm{BaSO_4(s)} = -349\ \text{kcal/mol}$

Match List I with List II. Choose the correct answer from the options given below:

In which of the following processes entropy increases? A. A liquid evaporates to vapour. B. Temperature of a crystalline solid lowered from 130 K to 0 K. C. 2 NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g) D. Cl₂(g) → 2 Cl(g) Choose the correct answer from the options given below:

The work done during reversible isothermal expansion of one mole of hydrogen gas at 25°C from pressure of 20 atmosphere to 10 atmosphere is: (Given: R = 2 cal K⁻¹ mol⁻¹)

Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

Which of the following p-V curve represents maximum work done?

The correct sequence of bond enthalpy of C-X bond is:

For irreversible expansion of an ideal gas under isothermal condition, the correct option is:

The correct option for free expansion of an ideal gas under adiabatic condition is

For the reaction, $2Cl(g) \longrightarrow Cl_2(g)$ the correct option is:

The volume occupied by $1.8\,\text{g}$ of water vapour at $374^{\circ}C$ and $1\,\text{bar}$ pressure will be given that $R = 0.083\,\text{bar L K}^{-1}\text{mol}^{-1}$.

The bond dissociation energies of X₂, Y₂ and XY are in the ratio of 1 : 0.5 : 1. ΔH for the formation of XY is −200 kJ mol⁻¹. The bond dissociation energy of X₂ will be

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy ΔU of the gas in joule will be

For a given reaction, ΔH = 35.5 kJ mol⁻¹ and ΔS = 83.6 JK⁻¹ mol⁻¹. The reaction is spontaneous at: (Assume that ΔH and ΔS do not vary with temperature)

For a sample of perfect gas when its pressure is changed isothermally from $P_i$ to $P_f$, the entropy change is given by:

If the $E^\circ_{cell}$ for a given reaction has a negative value, which of the following gives the correct relationships for the values of $\Delta G^\circ$ and $K_{eq}$?

The formation of the oxide ion, $\mathrm{O^{2-}(g)}$, from an oxygen atom requires first an exothermic and then an endothermic step as shown below: $$\mathrm{O(g) + e^- \rightarrow O^-(g)}; \qquad \Delta_f H^\circ = -141\;kJ\;mol^{-1}$$ $$\mathrm{O^-(g) + e^- \rightarrow O^{2-}(g)}; \qquad \Delta_f H^\circ = +780\;kJ\;mol^{-1}$$ Thus, the process of formation of O²⁻ in the gas phase is unfavourable even though O²⁻ is isoelectronic with neon. It is due to the fact that:

The heat of combustion of carbon to CO₂ is $-393.5\ \mathrm{kJ\ mol^{-1}}$. The heat released upon formation of 35.2 g of CO₂ from carbon and oxygen gas is:

Which of the following statements is correct for the spontaneous adsorption of a gas?

For the reaction: $$X₂O₄(l) → 2XO₂(g)$$ ΔU = 2.1 k cal, and ΔS = 20 cal K⁻¹ at 300 K. Hence ΔG is:

For a given exothermic reaction, Kₚ and K′ₚ are the equilibrium constants at temperatures T₁ and T₂, respectively. Assuming that the heat of reaction is constant in the temperature range between T₁ and T₂, it is readily observed that:

Equal volumes of two monoatomic gases A and B at same temperature and pressure are mixed. The ratio of specific heats (C$_p$/C$_v$) of the mixture will be:

Consider the following processes:

A bubble of air is underwater at temperature $15^\circ C$ and pressure $1.5\,bar$. If the bubble rises to the surface where the temperature is $25^\circ C$ and the pressure is $1.0\,bar$, what will happen to the volume of the bubble?

Match List I (Equations) with List II (Types of processes) and select the correct option.

For vaporization of water at 1 atmospheric pressure, ΔH and ΔS are 40.63 kJ mol⁻¹ and 108.8 J K⁻¹ mol⁻¹ respectively. The temperature at which Gibbs energy change (ΔG) for this transformation will be zero is:

The following two reactions are known: $$Fe_2O_3(s) + 3CO(g) \rightarrow 2Fe(s) + 3CO_2(g) \qquad \Delta H = -26.8\ kJ$$ $$FeO(s) + CO(g) \rightarrow Fe(s) + CO_2(g) \qquad \Delta H = -16.5\ kJ$$ The value of ΔH for the following reaction: $$Fe_2O_3(s) + CO(g) \rightarrow 2FeO(s) + CO_2(g)$$ is :

From the following bond energies: H–H bond energy = $431.37\;\text{kJ mol}^{-1}$ C=C bond energy = $606.10\;\text{kJ mol}^{-1}$ C–C bond energy = $336.49\;\text{kJ mol}^{-1}$ C–H bond energy = $410.50\;\text{kJ mol}^{-1}$ Enthalpy for the reaction:

The energy absorbed by each molecule $(A_2)$ of a substance is $4.4 \times 10^{-19}\,J$ and bond energy per molecule is $4.0 \times 10^{-19}\,J$. The kinetic energy of the molecule per atom will be:

The values of $\Delta H$ and $\Delta S$ for the reaction: $$\mathrm{C(graphite) + CO_2(g) \rightarrow 2CO(g)}$$ are 170 kJ and 170 J K⁻¹ respectively. This reaction will be spontaneous at:

Which of the following are not state functions? (I) q + w (II) q (III) w (IV) H − TS

Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434, 242 and 431 kJ mol⁻¹ respectively. Enthalpy of formation of HCl is

For the gas phase reaction, PCl₅(g) ⇌ PCl₃(g) + Cl₂(g) which of the following conditions is correct?

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

Assume each reaction is carried out in an open container. For which reaction will ΔH = ΔE?

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

The enthalpy of combustion of H₂, cyclohexene (C₆H₁₀) and cyclohexane (C₆H₁₂) are -241, -3800 and -3920 kJ mol⁻¹ respectively. Heat of hydrogenation of cyclohexene is:

A reaction occurs spontaneously if:

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?

The absolute enthalpy of neutralisation of the reaction: $$MgO(s) + 2HCl(aq) \rightarrow MgCl_2(aq) + H_2O(l)$$ will be: