Chemical Thermodynamics · JEE Main previous year questions

The enthalpy change for the conversion of $\frac{1}{2}{\mathrm{Cl}}_2(\text{ g})$ to ${\mathrm{Cl}}^{-}(\text{aq})$ is $(-)$ ___________ ${\text{kJmol}}^{-1}$ (Nearest integer) Given : ${\Delta }_{\mathrm{dis}}{\mathrm{H}}_{{\mathrm{Cl}}_{2(\mathrm{g})}}^{\ominus }=240{\text{ kJ mol}}^{-1}$, ${\Delta }_{\mathrm{eg}}{\mathrm{H}}_{{\mathrm{Cl}}_{(\mathrm{g})}}^{\ominus }=-350{\text{ kJ mol}}^{-1}$, ${\Delta }_{\mathrm{hyd}}{\mathrm{H}}_{{\mathrm{Cl}}_{(\mathrm{g})}^{-}}^{\ominus }=-380{\text{ kJ mol}}^{-1}$

Enthalpies of formation of ${\mathrm{CCl}}_4(\text{g}),{\mathrm{H}}_2\mathrm{O}(\mathrm{g}),{\mathrm{CO}}_2(\text{g})$ and $\mathrm{HCl}(\mathrm{g})$ are $-105,-242,-394$ and $-92{\text{ kJ mol}}^{-1}$ respectively. The magnitude of enthalpy of the reaction given below is ___________ ${\text{kJ mol}}^{-1}$. (nearest integer) ${\mathrm{CCl}}_4(\text{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{g})\to {\mathrm{CO}}_2(\text{g})+4\mathrm{HCl}(\mathrm{g})$

The number of alkali metal(s), from $\mathrm{Li},\mathrm{K},\mathrm{Cs},\mathrm{Rb}$ having ionization enthalpy greater than $400{\text{ kJ mol}}^{-1}$ and forming stable super oxide is ___________.

The bond dissociation energy is highest for

1. A.$\mathrm{C}{\mathrm{l}}_2$
2. B.${\mathrm{I}}_2$
3. C.$\mathrm{B}{\mathrm{r}}_2$
4. D.${\mathrm{F}}_2$

Inert gases have positive electron gain enthalpy. Its correct order is :

1. A.He < Ne < Kr < Xe
2. B.He < Xe < Kr < Ne
3. C.Xe < Kr < Ne < He
4. D.He < Kr < Xe < Ne

The number of incorrect statement/s from the following is/are ____ A. Water vapours are adsorbed by anhydrous calcium chloride. B. There is a decrease in surface energy during adsorption. C. As the adsorption proceeds, $\Delta$H becomes more and more negative. D. Adsorption is accompanied by decrease in entropy of the system.

For independent processes at $300\mathrm{K}$ $$\begin{array}{lll}\text{Process}& \Delta \mathrm{H}/\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}& \Delta \mathrm{S}/\mathrm{J}{\mathrm{K}}^{-1}\\ \text{A}& -25& -80\\ \text{B}& -22& 40\\ \text{C}& 25& -50\\ \text{D}& 22& 20\end{array}$$ The number of non-spontaneous processes from the following is ____

The first ionization enthalpy of Na, Mg and Si, respectively, are : 496, 737 and $786\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. The first ionization enthalpy ($\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$) of Al is :

1. A.487
2. B.768
3. C.577
4. D.856

When $600\mathrm{mL}$ of $0.2\mathrm{M}\mathrm{HN}{\mathrm{O}}_3$ is mixed with $400\mathrm{mL}$ of $0.1\mathrm{M}\mathrm{NaOH}$ solution in a flask, the rise in temperature of the flask is ________ $\times 10^{-2}{}^{\circ }\mathrm{C}$. (Enthalpy of neutralisation $=57\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ and Specific heat of water $=4.2\mathrm{J}{\mathrm{K}}^{-1}{\mathrm{g}}^{-1}$) (Neglect heat capacity of flask)

Which of the following 3d-metal ion will give the lowest enthalpy of hydration (${\Delta }_{\mathrm{hyd}}\mathrm{H}$) when dissolved in water ?

1. A.$\mathrm{C}{\mathrm{r}}^{2+}$
2. B.$\mathrm{M}{\mathrm{n}}^{2+}$
3. C.$\mathrm{F}{\mathrm{e}}^{2+}$
4. D.$\mathrm{C}{\mathrm{o}}^{2+}$

Given below are two statements: One is labelled as Assertion $\mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$. Assertion A : The reduction of a metal oxide is easier if the metal formed is in liquid state than solid state. Reason $\mathbf{R}$ : The value of $\Delta G^{\ominus }$ becomes more on negative side as entropy is higher in liquid state than solid state. In the light of the above statements, choose the most appropriate answer from the options given below

1. A.Both A and R are correct and R is the correct explanation of A
2. B.Both A and R are correct but R is NOT the correct explanation of A
3. C.A is correct but R is not correct
4. D.A is not correct but R is correct

An element A of group 1 shows similarity to an element B belonging to group 2. If A has maximum hydration enthalpy in group 1 then B is :

1. A.Mg
2. B.Be
3. C.Ca
4. D.Sr

A gas (Molar mass $=280\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$) was burnt in excess ${\mathrm{O}}_2$ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from $298.0\mathrm{K}$ to $298.45\mathrm{K}$. If the heat capacity of calorimeter is $2.5\mathrm{kJ}{\mathrm{K}}^{-1}$ and enthalpy of combustion of gas is $9\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ then amount of gas burnt is ____ $\mathrm{g}$. (Nearest Integer)

$2.4\mathrm{g}$ coal is burnt in a bomb calorimeter in excess of oxygen at $298\mathrm{K}$ and $1\mathrm{atm}$ pressure. The temperature of the calorimeter rises from $298\mathrm{K}$ to $300\mathrm{K}$. The enthalpy change during the combustion of coal is $-x\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. The value of $x$ is ____. (Nearest Integer) (Given : Heat capacity of bomb calorimeter $20.0\mathrm{kJ}{\mathrm{K}}^{-1}$. Assume coal to be pure carbon)

For micelle formation, which of the following statements are correct? A. Micelle formation is an exothermic process. B. Micelle formation is an endothermic process. C. The entropy change is positive. D. The entropy change is negative.

1. A.A and D only
2. B.A and C only
3. C.B and C only
4. D.B and D only

While performing a thermodynamics experiment, a student made the following observations. $\mathrm{HCl}+\mathrm{NaOH}\to \mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}\mathrm{\Delta H}=-57.3\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ $\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}+\mathrm{NaOH}\to \mathrm{C}{\mathrm{H}}_3\mathrm{COONa}+{\mathrm{H}}_2\mathrm{O}\mathrm{\Delta H}=-55.3\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ The enthalpy of ionization of $\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$ as calculated by the student is ___________ $\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. (nearest integer)

The correct order of electron gain enthalpy ($-\text{ ve}$ value) is :

1. A.$O>S>Se>Te$
2. B.$O<S<Se<Te$
3. C.$O<S>Se>Te$
4. D.$O<S>Se<Te$

Match List-I with List-II. $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ \text{(A)}& \text{Spontaneous process}& \text{(I)}& \Delta H<0\\ \text{(B)}& \text{Process with }\Delta P=0,\Delta T=0& \text{(II)}& \Delta G_{T,P}<0\\ \text{(C)}& \Delta H_{reaction}& \text{(III)}& \text{Isothermal and isobaric process}\\ \text{(D)}& \text{Exothermic Process}& \text{(IV)}& \text{[Bond energies of molecules in reactants]}-\text{[Bond energies of product molecules]}\end{array}$$ Choose the correct answer from the options given below :

1. A.(A) - (III), (B) - (II), (C) - (IV), (D) - (I)
2. B.(A) - (II), (B) - (III), (C) - (IV), (D) - (I)
3. C.(A) - (II), (B) - (III), (C) - (I), (D) - (IV)
4. D.(A) - (II), (B) - (I), (C) - (III), (D) - (IV)

For complete combustion of methanol $\mathrm{C}{\mathrm{H}}_3\mathrm{OH}(\mathrm{l})+\frac{3}{2}{\mathrm{O}}_2(\mathrm{g})\to \mathrm{C}{\mathrm{O}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$ the amount of heat produced as measured by bomb calorimeter is $726{\text{ kJ mol}}^{-1}$ at $27^{\circ }\text{C}$. The enthalpy of combustion for the reaction is $-x{\text{ kJ mol}}^{-1}$, where x is ________. (Nearest integer) (Given : $\mathrm{R}=8.3{\text{ JK}}^{-1}{\text{ mol}}^{-1}$)

$\mathrm{Cu}(\mathrm{s})+\mathrm{S}{\mathrm{n}}^{2+}(0.001\mathrm{M})\to \mathrm{C}{\mathrm{u}}^{2+}(0.01\mathrm{M})+\mathrm{Sn}(\mathrm{s})$ The Gibbs free energy change for the above reaction at $298\mathrm{K}$ is $x\times 10^{-1}\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. The value of $x$ is ____. [nearest integer] [Given : $E_{\mathrm{C}{\mathrm{u}}^{2+}/Cu}^{\ominus }=0.34\mathrm{V}$ ; $E_{\mathrm{S}{\mathrm{n}}^{2+}/Sn}^{\ominus }=-0.14\mathrm{V}$ ; $\mathrm{F}=96500\mathrm{C}\mathrm{mo}{\mathrm{l}}^{-1}$]

The standard entropy change for the reaction $4\mathrm{Fe}(\mathrm{s})+3{\mathrm{O}}_2(\mathrm{g})\to 2{\mathrm{Fe}}_2{\mathrm{O}}_3(\mathrm{s})$ is $-550{\text{ J K}}^{-1}$ at $298\text{ K}$. [Given : The standard enthalpy change for the reaction is $-165{\text{ kJ mol}}^{-1}$]. The temperature in $\mathrm{K}$ at which the reaction attains equilibrium is $\underline{}$. (Nearest Integer)

At $25^{\circ }\text{C}$ and $1\text{ atm}$ pressure, the enthalpies of combustion are as given below : | Substance | ${\mathrm{H}}_2$ | $\mathrm{C}\text{ (graphite)}$ | ${\mathrm{C}}_2{\mathrm{H}}_6(g)$ | | :--- | :--- | :--- | :--- | | $\frac{{\Delta }_{\mathrm{c}}{H}^{\ominus }}{{\text{kJ mol}}^{-1}}$ | $-286.0$ | $-394.0$ | $-1560.0$ | The enthalpy of formation of ethane is

1. A.$+54.0{\text{ kJ mol}}^{-1}$
2. B.$-68.0{\text{ kJ mol}}^{-1}$
3. C.$-86.0{\text{ kJ mol}}^{-1}$
4. D.$+97.0{\text{ kJ mol}}^{-1}$

The correct order of first ionisation enthalpy is :

1. A.Mg < S < Al < P
2. B.Mg < Al < S < P
3. C.Al < Mg < S < P
4. D.Mg < Al < P < S

At 298.2 K the relationship between enthalpy of bond dissociation (in $\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$) for hydrogen ($E_H$) and its isotope, deuterium ($E_D$), is best described by :

1. A.$E_H=\frac{1}{2}{E}_D$
2. B.$E_H=E_D$
3. C.$E_H\simeq E_D-7.5$
4. D.$E_H=2E_D$

At 298 K, the enthalpy of fusion of a solid (X) is $2.8\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ and the enthalpy of vaporisation of the liquid (X) is $98.2\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. The enthalpy of sublimation of the substance (X) in $\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ is ____. (in nearest integer)