An irreversible process occuring isothermally in an isolated system leads to

(1) Zero entropy

(2) An increase in the total entropy of the system

(3) A decrease in the total entropy of the system

(4) None of these

Enthalpy and entropy change for a chemical reaction are –2.5 × 10³ cal and 7.4 cal deg^–1 respectively. Reaction at 298 K is -

(1) Spontaneous

(2) Reversible

(3) Irreversible

(4) Non-spontaneous

The entropy changed involved in the conversion of 1 mole of liquid water at 373 K to vapour at the same temperature will be $[\Delta H_{\text{vap}}=2.257kJ/gm]$ [MP PET 2002]

(1) 0.119 kJ

(2) 0.109 kJ

(3) 0.129 kJ

(4) 0.120 kJ

When a liquid boils, there is [JIPMER 2002]

(1) An increase in entropy

(2) A decrease in entropy

(3) An increase in heat of vaporization

(4) An increase in free energy

For a carnot engine, the source is at 500 K and the sink at 300 K. What is efficiency of this engine

(1) 0.2

(2) 0.4

(3) 0.6

(4) 0.3

A solution of 500 ml of 0.2 M KOH and 500 ml of 0.2 M HCl is mixed and stirred; the rise in temperature is T₁. The experiment is repeated using 250 ml each of solution, the temperature raised is T₂. Which of the following is true .

(1) T₁ = T₂

(2) T₁ = 2T₂

(3) T₁ = 4T₂

(4) T₂ = 9T₁

The heat of formation of HCl(g) from the reaction

H₂(g) + Cl₂(g) ; $∆H = -44 kcal$ is

1. +44 kcal

2. -44 kcal

3. +22 kcal

4. -22 kcal

The heat of neutralisation of HCl by NaOH is -55.9 kJ/mole. If the heat of neutralisation of HCN by NaOH is -12.1 kJ/mole, then energy of dissociation of HCN is-

1. -43.8 kJ

2. 43.8 kJ

3. 68 kJ

4. -68 kJ

In which case of mixing of a strong acid and a base, each of 1(N) concentration, temperature-increase is the highest ?

1. 20 ml acid and 30 ml alkali

2. 10 ml acid and 40 ml alkali

3. 25 ml acid and 25 ml alkali

4. 35 ml acid and 15 ml alkali

The heats of neutralisation of four acids A, B, C and D are -13.7, -9.4, -11.2 and -12.4 kcal respectively when they are neutralised by a common base. The acidic character obeys the order :

1. A>B>C>D

2. A>D>C>B

3. D>C>B>A

4. D>B>C>A