All the naturally occurring processes, i.e., spontaneous proceed spontaneously in a direction which leads to:

(1) decrease of free energy                     

(2) increase of free energy

(3) decrease of entropy                           

(4) increase of enthalpy

Warming ammonium chloride with sodium hydroxide in a test tube is an example of:

1. closed system                      2. Isolated system

3. open system                        4. None of these

Predict which of the following reaction(s) has a positive entropy change?

(i) Ag⁺ (aq) + Cl^-(aq) $\to$AgCl(s)

(ii) NH₄Cl(g) $\to$NH₃(g) + HCl(g)

(iii) 2NH₃(g)$\to$N₂(g) + 3H₂(g)

(1) i & ii

(2) iii

(3) ii & iii

(4) ii

For the following given equations and $∆\mathrm{H}°$ values, determine the enthalpy of reaction at 298 K for the reaction:

C₂H₄(g) + 6F₂(g) $\to$ 2CF₄(g) + 4HF(g)

H₂(g) + F₂(g) $\to$ 2HF(g)       $∆{\mathrm{H}}_1^{°}$= -537 kJ

C(s) + 2F₂(g) $\to$CF₄(g)         $∆{\mathrm{H}}_2^{°}$=-680 kJ

2C(s) + 2H₂(g) $\to$C₂H₄(g)    $∆{\mathrm{H}}_3^{°}$= 52 kJ

1. –1165 kJ

2. –2486 kJ

3. +1165 kJ

4. +2486 kJ

If $∆{\mathrm{H}}_{\mathrm{f}}^{°}$(C₂H₄) and $∆{\mathrm{H}}_{\mathrm{f}}^{°}$(C₂H₆) are x₁ and x₂ kcal/mol then heat of hydrogenation of C₂H₄ is :-

(1) x₁ + x₂

(2) x₁ - x₂

(3) x₂ - x₁

(4) x₁ + 2x₂

For the reaction, X₂O₄(l) $\to$2XO₂(g)

$∆$U = 2.1 kcal, $∆$S = 20 cal K^-1 at 300 K. Hence, $∆$G is

(1) 2.7 kcal

(2) -2.7 kcal

(3) 9.3 kcal

(4) -9.3 kcal

The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0°C is

(a) 10.52 cal/(mol K)

(b) 21.04 cal/(mol K)

(c) 5.260 cal/(mol K)

(d) 0.526 cal/(mol K)

The enthalpy and entropy change for the reaction :

Br₂(l)+Cl₂(g) $\to$ 2BrCl(g) are 30 kJ mol^-1 and 105 JK^-1 mol^-1 respectively.

The temperature at which the reaction will be in equilibrium is :

1. 285.7 K

2. 273 K

3. 450 K

4. 300 K

The temperature of the system decreases in an

(1) Adiabatic compression

(2) Isothermal compression

(3) Isothermal expansion

(4) Adiabatic expansion

Mark the correct statement 

(1) For a chemical reaction to be feasible, ΔG should be zero

(2) Entropy is a measure of order in a system

(3) For a chemical reaction to be feasible, ΔG should be positive

(4) The total energy of an isolated system is constant