JEE Chemical Thermodynamics PYQs with Solutions PDF

Consider the following data :
$$\Delta_f H^\ominus$$ (methane, g) = - X kJ $$mol^{-1}$$
Enthalpy of sublimation of graphite = Y kJ $$mol^{-1}$$
Dissociation enthalpy of $$H_{2}$$ = Zkj $$mol^{-1}$$
The bond enthalpy of C - H bond is given by :

Which of the following graphs between pressure 'p' versus volume 'V' represents the maximum work done?

For the reaction $$N_{2}O_{4}\rightleftharpoons2NO_{2}$$ , graph is plotted as shown below. Identify correct statements.
A. Standard free energy change for the reaction is $$-5.40kJmol^{-1}$$.
B. As $$\triangle G^{\ominus}$$ in graph is positive, $$N_{2}O_{4}$$ will not dissociate into $$NO_{2}$$ at all.
C. Reverse reaction will go to completion.
D. When 1 mole of $$N_{2}O_{4}$$ changes into equilibrium mixture, value of $$\triangle G^{\ominus}$$ = -0.84kJ $$mol^{-1}$$.
E. When 2 mole of $$NO_{2}$$ changes into equilibrium mixture, $$\triangle G^{\ominus}$$ for equilibrium mixture is -6.24kJ $$mol^{-1}$$.

Choose the correct answer from the options given below:

Use the following data :

One mole each of $$A_{2}(g)$$ and $$B_{2}(g)$$ are taken in a 1 L closed flask and allowed to establish the equilibrium at 500K
$$A_{2}(g)+B_{2}(g)\rightleftharpoons2AB(g)$$
The value of x $$(in kJ mol^{-1})$$ is ____ . (Nearest integer)
(Given: log K=2.2 R= 8.3 kJ $$K^{-1} mol^{-1}$$)

If the enthalpy of sublimation of Li is 155 kj $$mol^{-1}$$, enthalpy of dissociation of $$F_{2}$$ is 150 kj $$mol^{-1}$$, ionization enthalpy of Li is 520 kj $$mol^{-1}$$, electron gain enthalpy of F is - 313 kj $$mol^{-1}$$, standard enthalpy of formation of LiF is - 594 kj $$mol^{-1}$$. The magnitude of lattice enthalpy of LiF is _________ kJ $$mol_{-1}$$. (Nearest Integer)

A cup of water at 5°C (system) is placed in a microwave oven and the oven is turned on for one minute during which the water begins to boil. Which of the following option is true ?

Match the LIST-I with LIST-II

Choose the correct answer from the options given below:

Match the LIST-I with LIST-II

Choose the correct answer from the options given befow:

The heat of atomisation of methane and ethane are 'x' kJ $$mol^{-1}$$ and 'y' kJ $$mol^{-1}$$ respectively. The longest wavelength ($$\lambda$$) of light capable of breaking the C-C bond
can be expressed in SI unit as:

$$20.0 dm^{3}$$ of an ideal gas 'X' at 600 K and 0.5 MPa undergoes isothermal reversible expansion until pressme of the gas is 0.2 MPa. Which of the following option is correct?
(Given: $$\log 2 = 0.30 10 and \log 5 = 0.6989$$)

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

Consider the following cases of standard enthalpy of reaction ($$\Delta H_{r}^{\circ}$$ in kJ $$mol^{-1}$$)
$$C_{2}H_{6}(g)+\frac{7}{2}O_{2}(g) \rightarrow 2CO_{2}(g)+3H_{2}O(1)\Delta H_{1}^{\circ}=-1550$$
$$C(graphite)+O_{2}(g)\rightarrow CO_{2}(g)$$ $$\Delta H_{2}^{\circ}=-393.5$$ The magnitude of $$\Delta H_{fC_{2}H_{6}(g)}^{\circ}$$ is_______
$$H_{2}(g)+\frac{1}{2}O_{2}(g)\rightarrow H_{2}O(1)$$ $$\Delta H_{3}^{\circ}=-286$$
$$kJ mol^{-1}$$ (Nearest integer).

A liquid when kept inside a thermally insulated closed vessel $$25^{o}C$$ at was mechanically stirred from outside. What will be the correct option for the following thermodynamic parameters ?

The effect of temperature on spontaneity of reactions are represented as :

The bond dissociation enthalpy of $$X_{2}\Delta H_{bond}$$ calculated from the given data is_____$$kJmol^{-1}$$.(Nearest integer)
$$M^{+}X^{-}(s)\rightarrow M^{+}(g)+X^{-}(g)\Delta H_{lattice}^{*}=800kJmol^{-1}\\M(s)\rightarrow M(g)\Delta H_{sub}^{\circ}=100kJmol^{-1}\\M(g)\rightarrow M^{+}(g)+e^{-}(g)\Delta H_{i}=500kJmol^{-1}X(g)+e^{-}(g)\rightarrow X^{-}(g)\Delta H_{eg}^{*}=-300kJmol^{-1}\\M(g)+\frac{1}{2}X_{2}(g)\rightarrow M^{+}X^{-}(s)\Delta H_{f}^{\circ}=-400kJmol^{-1}$$
[Given : $$M^{+}X^{-}$$ is a pure ionic compound and X forms a diatomic molecule $$X_{2}$$ in gaseous state]

Let us consider an endothermic reaction which is non-spontaneous at the freezing point of water. However, the reaction is spontaneous at boiling point of water. Choose the correct option.

Standard entropies of  $$X_2,\ Y_2$$  and  $$XY_5$$  are  $$70,\ 50$$  and  $$110\,J\,K^{-1}mol^{-1}$$ respectively. The temperature in Kelvin at which the reaction $$\frac{1}{2}X_2 + \frac{5}{2}Y_2 \rightleftharpoons XY_5 \Delta H^\ominus = -35\,kJ\,mol^{-1}$$ will be at equilibrium is $$\underline{\hspace{2cm}}$$  (Nearest integer).}

Which of the following mixing of 1 M base and 1 M acid leads to the largest increase in temperature?

$$S(g) + \frac{3}{2}O_2(g) \rightarrow SO_3(g) + 2x\,\text{kcal} \\SO_2(g) + \frac{1}{2}O_2(g) \rightarrow SO_3(g) + y\,\text{kcal}\\\text{The heat of formation of } SO_2(g) \text{ is given by:}$$

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K . If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

The formation enthalpies, $$\Delta H_{f}\ominus$$ for $$H_{g}$$ and $$O_{g}$$ are 220.0 and $$250.0 kJ mol^{-1}$$, respectively, at 298.15 K , and $$\Delta H_{f}\ominus$$ for $$H_{2}O_{g}$$ is $$-242.5 kJ mol^{-1}$$ at the same temperature. The average bond enthalpy of the $$O-H$$ bond in water at 298.15 K is __________$$kJ mol^{-1}$$(nearest integer).

J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given : $$R = 8.3 J K^{-1}mol^{-1}$$

Ice at $$-5^{\circ}C$$ is heated to become vapor with temperature of $$110^{\circ}C$$ at atmospheric pressure. The entropy change associated with this process can be obtained from

The standard enthalpy and standard entropy of decomposition of $$N_{2}O_{4}$$ to $$NO_{2}$$ are 55.0 kJ $$mol^{-1}$$ and 175.0 J/K/mol respectively. The standard free energy change for this reaction at $$25^{\circ}C$$ in J $$mol^{-1}$$ is ______ (Nearest integer)

If $$C(\text{diamond}) \rightarrow C(\text{graphite}) + X\,\text{kJ mol}^{-1} C(\text{diamond}) + O_2(g) \rightarrow CO_2(g) + Y\,\text{kJ mol}^{-1}C(\text{graphite}) + O_2(g) \rightarrow CO_2(g) + Z\,\text{kJ mol}^{-1}$$ at constant temperature. Then

The enthalpy of formation of ethane (C₂H₆) from ethylene by addition of hydrogen where the bond-energies of C−H, C−C, C=C, H−H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is ______ kJ.

An ideal gas undergoes a cyclic transformation starting from the point A and coming back to the same point by tracing the path $$ A \rightarrow B \rightarrow C \rightarrow D \rightarrow A$$ as shown in the three cases above. Choose the correct option regarding $$\Delta U$$ :

Consider the following data : Heat of formation of $$CO_{2}$$(g)= -393.5 kJ $$mol^{-1}$$ Heat of formation of $$H_{2}0$$(l) = - 286.0 kJ $$mol^{-1}$$ Heat of combustion of benzene =-3267.0 kJ $$mol^{-1}$$ The heat of formation of benzene is _ . (Nearest integer)

Choose the correct option for free expansion of an ideal gas under adiabatic condition from the following :

For a certain reaction at 300 K, K = 10, then $$\Delta G°$$ for the same reaction is - ______ $$\times$$ $$10^{-1}$$  $$kJ mol^{-1}$$. (Given $$R = 8.314 \text{ J K}^{-1} \text{mol}^{-1}$$)

If three moles of an ideal gas at $$300$$ K expand isothermally from $$30 \text{ dm}^3$$ to $$45 \text{ dm}^3$$ against a constant opposing pressure of $$80$$ kPa, then the amount of heat transferred is _________ J.

For a certain thermochemical reaction $$M \rightarrow N$$ at $$T = 400$$ K, $$\Delta H^o = 77.2$$ kJ mol$$^{-1}$$, $$\Delta S^o = 122$$ J K$$^{-1}$$, log equilibrium constant ($$\log K$$) is $$-$$ _____ $$\times 10^{-1}$$.

Which of the following is not correct?

Standard enthalpy of vapourisation for $$CCl_4$$ is $$30.5$$ kJ mol$$^{-1}$$. Heat required for vapourisation of $$284$$ g of $$CCl_4$$ at constant temperature is ______ kJ. (Given molar mass in g mol$$^{-1}$$; C = 12, Cl = 35.5)

An ideal gas undergoes a cyclic transformation starting from the point $$A$$ and coming back to the same point by tracing the path $$A \rightarrow B \rightarrow C \rightarrow A$$ as shown in the diagram. The total work done in the process is _____ J.

Two reactions are given below:
$$2Fe_{(s)} + \frac{3}{2}O_{2(g)} \rightarrow Fe_2O_{3(s)}$$, $$\Delta H° = -822$$ kJ/mol
$$C_{(s)} + \frac{1}{2}O_{2(g)} \rightarrow CO_{(g)}$$, $$\Delta H° = -110$$ kJ/mol
Then enthalpy change for following reaction:
$$3C_{(s)} + Fe_2O_{3(s)} \rightarrow 2Fe_{(s)} + 3CO_{(g)}$$

Consider the following reaction at 298 K. $$\frac{3}{2}O_{2(g)} \rightleftharpoons O_{3(g)}$$, $$K_p = 2.47 \times 10^{-29}$$. $$\Delta_r G^0$$ for the reaction is _________ kJ. (Given $$R = 8.314 \text{ JK}^{-1}\text{mol}^{-1}$$) Round off your answer to the nearest integer.

If 5 moles of an ideal gas expands from 10 L to a volume of 100 L at 300 K under isothermal and reversible condition then work, $$w$$, is $$-x$$ J. The value of $$x$$ is (Given $$R = 8.314$$ J K$$^{-1}$$ mol$$^{-1}$$)

Three moles of an ideal gas are compressed isothermally from $$60$$ L to $$20$$ L using constant pressure of $$5$$ atm. Heat exchange $$Q$$ for the compression is $$-$$ ______ Lit. atm.

Combustion of 1 mole of benzene is expressed at $$C_6H_6(l) + \frac{15}{2}O_2(g) \rightarrow 6CO_2(g) + 3H_2O(l)$$. The standard enthalpy of combustion of 2 mol of benzene is $$-'x'$$ kJ. $$x =$$ ______ Given: 1. Standard enthalpy of formation of 1 mol of $$C_6H_6(l)$$, for the reaction $$6C \text{(graphite)} + 3H_2(g) \rightarrow C_6H_6(l)$$ is $$48.5 \text{ kJ mol}^{-1}$$. 2. Standard enthalpy of formation of 1 mol of $$CO_2(g)$$, for the reaction $$C \text{(graphite)} + O_2(g) \rightarrow CO_2(g)$$ is $$-393.5 \text{ kJ mol}^{-1}$$. 3. Standard enthalpy of formation of 1 mol of $$H_2O(l)$$, for the reaction $$H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(l)$$ is $$-286 \text{ kJ mol}^{-1}$$.

Which of the following gives a positive test with ninhydrin?

DNA molecule contains 4 bases whose structures are shown below. One of the structures is not correct, identify the incorrect base structure.

Identify the product (A) in the following reaction.

The incorrect statements regarding enzymes are : (A) Enzymes are biocatalysts. (B) Enzymes are non-specific and can catalyse different kinds of reactions. (C) Most Enzymes are globular proteins. (D) Enzyme - oxidase catalyses the hydrolysis of maltose into glucose. Choose the correct answer from the option given below :

The incorrect statement regarding the given structure is

The total number of carbon atoms present in tyrosine, an amino acid, is _____

Total number of essential amino acid among the given list of amino acids is _______ Arginine, Phenylalanine, Aspartic acid, Cysteine, Histidine, Valine, Proline

When $$\Delta H_{vap} = 30 \text{ kJ/mol}$$ and $$\Delta S_{vap} = 75 \text{ J mol}^{-1} \text{K}^{-1}$$, then the temperature of vapour, at one atmosphere is ______ K.

At 25°C, the enthalpy of the following processes are given:
$$H_2(g) + O_2(g) \rightarrow 2OH(g) \quad \Delta H^o = 78 \text{ kJ mol}^{-1}$$
$$H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(g) \quad \Delta H^o = -242 \text{ kJ mol}^{-1}$$
$$H_2(g) \rightarrow 2H(g) \quad \Delta H^o = 436 \text{ kJ mol}^{-1}$$
$$\frac{1}{2}O_2(g) \rightarrow O(g) \quad \Delta H^o = 249 \text{ kJ mol}^{-1}$$
What would be the value of X for the following reaction? (Nearest integer)
$$H_2O(g) \rightarrow H(g) + OH(g) \quad \Delta H^o = X \text{ kJ mol}^{-1}$$

0.3 g of ethane undergoes combustion at $$27°C$$ in a bomb calorimeter. The temperature of calorimeter system (including the water) is found to rise by $$0.5°C$$. The heat evolved during combustion of ethane at constant pressure is ______ $$\text{kJmol}^{-1}$$.
(Nearest integer)
[Given : The heat capacity of the calorimeter system is $$20 \text{ kJ K}^{-1}$$, $$R = 8.3 \text{ JK}^{-1} \text{ mol}^{-1}$$. Atomic mass of C and H are 12 and 1 $$\text{g mol}^{-1}$$ respectively]