At constant pressure and temperature, the direction of any chemical reaction is one where, the...... decrease.

(a) entropy                (b) enthalpy

(c) Gibbs energy        (d) none of these

Which is correct at equilibrium?

1. $∆$H = 0              2. $∆$G_Total=0

3. $∆$S_Total=0          4. $∆$E=0

'The free energy change due to a reaction is zero when

1. The reactants are initially mixed.

2.  A catalyst is added

3. The system is at equilibrium

4. The reactants are completely consumed

18 g of ice is converted into water at 0$°$C and 1 atm. The entropy of H₂O_(s) and H₂O_(l) are 38.2 and 60 J K^-1 mol^-1 respectively. the enthalpy for this conversion will be

(1) 5951.4 J/mol

(2) 595.14 J/mol

(3) -595.14 J/mol

(4) None of these

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

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

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

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

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

When enthalpy and entropy change for a chemical reaction are –2.5 × 10³ cal and 7.4 cal deg^–1 respectively. Predict the reaction at 298 K is [AFMC 1998; MH CET 1999; CBSE PMT 2000]

(1) Spontaneous

(2) Reversible

(3) Irreversible

(4) Non-spontaneous

Which of the following is not a correct statement? [ (Engg.) 2002]

(1) When ΔG is negative, the process is spontaneous

(2) When ΔG is zero, the process is in a state of equilibrium

(3) When ΔG is positive, the process is non-spontaneous

(4) None of these

For a reaction at equilibrium-

1. $∆G=∆G^{\circ }=0$

2. $∆G=0 but not ∆G^{\circ }$

3. $∆G^{\circ }=0 but not ∆G$

4. $∆G=∆G^{\circ }\ne 0$

Following reaction occurs at ${25}^{\circ }C$ :

$2NO\left(g, 1\times {10}^{-5}atm\right)+C{l}_2\left(g, 1\times {10}^{-2}atm\right)\rightleftharpoons 2NOCl\left(g, 1\times {10}^{-2}atm\right)∆G^{\circ }$ is-

1. -45.65 kJ

2. -28.53 kJ

3. -22.82 kJ

4. -57.06 kJ

If a process is both endothermic and spontaneous, then :

1. $∆S>0$

2. $∆S<0$

3. $∆H<0$

4. $∆G>0$