For isothermal expansion of an ideal gas, the correct combination of the thermodynamic parameters will be

• $∆$U = 0; Q = 0; W ≠ 0 and $∆$H ≠  0

• $∆$U ≠ 0; Q ≠ 0; W ≠ 0 and $∆$H =  0

• $∆$U = 0; Q ≠ 0; W = 0 and $∆$H ≠  0

• $∆$U = 0; Q ≠ 0; W ≠ 0 and $∆$H =  0

The standard Gibbs free energy change ($∆$G°) at 25°C for the dissociation of N₂O₄(g) to NO₂(g) is (given, equilibrium constant = 0.15, R = 8.314 JK/mol)

• 1.1 kJ

• 4.7 kJ

• 8.1 kJ

• 38.2 kJ

The condition of spontaneity of a process is

• lowering of entropy at constant temperature and pressure

• lowering of Gibbs free energy of system at constant temperature and pressure

• increase of entropy of system at constant temperature and pressure

• increase of Gibbs free energy of the universe at constant temperature and pressure

Identify the correct statement from the following in a chemical reaction

• The entropy always increases

• The change in entropy along with suitable change in enthalpy decides the rate of reaction

• The enthalpy always decreases

• Both the enthalpy and the entropy remain constant

A plot of ln K against $\frac{1}{\mathrm{T}}$ (abscissa) is expected to be a straight line with intercept on ordinate axis equal to

• $\frac{∆\mathrm{S}°}{2.303 \mathrm{R}}$

• $\frac{∆\mathrm{S}°}{\mathrm{R}}$

• $-\frac{∆\mathrm{S}°}{\mathrm{R}}$

• R × $∆\mathrm{S}°$

Which of the following is correct?

• Evaporation of water causes an increase in disorder of the system

• Melting of ice causes a decrease in randomness of the system

• Condensation of steam causes an increase in disorder of the system

• There is practically no change in the randomness of the system when water is evaporated

In which of the following reactions will $∆$U be equal to $∆$H?

• ${\mathrm{H}}_2\left(\mathrm{g}\right) +\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

• ${\mathrm{H}}_2\left(\mathrm{g}\right) + {\mathrm{I}}_2\left(\mathrm{g}\right) \to 2\mathrm{HI}\left(\mathrm{g}\right)$

• ${\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right) \to 2{\mathrm{NO}}_2\left(\mathrm{g}\right)$

• $2{\mathrm{SO}}_4\left(\mathrm{g}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) \to 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

48.

For the reaction

N₂ (g) + 3H₂ (g) $\rightleftharpoons$ 2NH₃ (g) $∆$H is equal to

• $∆$E - 2RT

• $∆$E - RT

• $∆$E + RT

• $∆$E + 2RT

Given, $∆$G°=-nFE°_cell and $∆$G° = -RT ln k. The value of n = 2 will be given by the slope of which line in the figure

• OA

• OB

• OC

• OD

The standard molar heat of formation of ethane, CO₂ and water (l) are respectively -21.1, -94.1 and -68.3 kcal. The standard molar heat of combustion of ethane will be

• -372 kcal

• 162 kcal

• -240 kcal

• 183.5 kcal