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

(1) If $∆$G_system > 0, the process is spontaneous

(2) If $∆$G_system = 0, the system has attained equilibrium

(3) If $∆$G_system = 0, the system is still moving in a particular direction

(4) If $∆$G_system < 0, the process is not spontaneous

The enthalpy and entropy change for the reaction :

Br₂ (l) + Cl₂ (g)$\to$ 2BrCl (g)

are 30 kJ mol^-1 and 105 J K^-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 per mol respectively. Heat of hydrogenation of cyclohexene is:

(a) -121 kJ per mol

(b) +121 kJ per mol

(c) +242 kJ per mol

(d) -242 kJ per mol

Consider the reactionat 300K

H₂₍₉₎ + Cl₂₍₉₎ →2HCI_(g), ΔH° = — 185 KJ

If 3 mole of H₂ completely react with 3 mol of Cl₂ to form Cl, $∆$U° of the reaction will be

(1) Zero

(2) –185 KJ

(3) -555 KJ

(4) None

For a perfectly crystalline solid C_pm = aT³, where a is constant. If C_pm is 0.42 J/K–mol at 10 K, molar entropy at 10 K is

1. 0.42 J/K–mol

2. 0.14 J/K–mol

3. 4.2 J/K–mol

4. zero

One mole of an ideal monoatomic gas expands isothermally against constant external pressure of 1 atm from initial volume of 1L to a state where its final pressure becomes equal to external pressure. If initial temperature of gas is 300 K then total entropy change of system in the above process is :

[R = 0.082 L atm mol^–1 K^–1 = 8.3 J mo1^–1K^–1].

(1) 0

(2) Rln (24.6)

(3) Rln (2490)

(4) $\frac{3}{2}$Rln(24.6)

At 1000 K water vapour at 1 atm. has been found to be dissociated into H₂ and O₂ to the extent of 3 x 10^–6 %.Calculate the free energy decrease of the system, assuming ideal behaviour.

(1) –ΔG = 90,060 cal

(2) –ΔG = 20 cal

(3) –ΔG = 480 cal

(4) –ΔG = –45760 cal

An ideal gas is taken from the same initial pressure P₁ to the same final pressure P₂ by three different processes. If it is known that point 1 corresponds to a reversible adiabatic and point 2 corresponds to a single stage adiabatic then

(1) Point 3 may be a two stage adiabatic.

(2) the average K.E. of the gas is maximum at point 1

(3) Work done by surrounding in reaching point number '3' will be maximum

(4) If point4 and point 5 lie along a reversible isotherm then T₅ < T₁.

During winters, moisture condenses in the form of dew and can be seen on plant leaves and grass. The entropy of the system in such cases decreases as liquids possess lesser disorder as compared to gases. With reference to the second law, which statement is correct, for the above process ?

(1) The randomness of the universe decreases

(2) The randomness of the surroundings decreases

(3) Increase is randomness of surroundings equals the decrease in randomness of system

(4) The increase in randomness of the surroundings is greater as compared to the decrease in randomnessof the system.

For which process will $∆$H° and $∆$G° be expected to be most similar.

(1) 2Al(s) + Al₂O₃(s) → 2Fe(s) + A_l2O₃(s)

(2) 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

(3) 2NO₂(g) → N₂O₄(g)

(4) 2H₂(g) + O₂(g) → 2H₂O(g)