A system that can neither exchange matter nor energy with the surroundings is classified as:

1. Open system

2. Isolated system

3. Closed system

4. Both (1) & (2)

The standard enthalpies of the formation of  NO₂(g) and N₂O₄(g) are 8 kcal mol^–1 and 2 kcal mol^–1 respectively. The heat of dimerization of NO₂ in the gaseous state is: 

The standard enthalpy of vaporization ${∆}_{\mathrm{vap}}{\mathrm{H}}^{\mathrm{o}}$ for water at 100 ^oC is 40.66 kJ mol^–1. The internal energy of vaporization of water at 100 ^oC (in kJ mol^–1) is: 
(Assume water vapour behaves like an ideal gas.)

1. +37.56

2. –43.76

3. +43.76

4. +40.66

Under the isothermal condition, a gas at \(300 \mathrm{~K}\) expands from \(0.1 \mathrm{~L}\) to \(0.25 \mathrm{~L}\) against a constant external pressure of 2 bar. The work done by the gas is:
1. \(30 ~\mathrm {J} \)
2. \(-30 ~\mathrm{J} \)
3. \(5~ \mathrm{kJ}\)
4. \(25~ \mathrm{J}\)

For the isothermal reversible expansion of an ideal gas: 

1. $∆\mathrm{H}>0 \mathrm{and} ∆\mathrm{U}=0$

2. $∆\mathrm{H}>0 \mathrm{and} ∆\mathrm{U}<0$

3. $∆\mathrm{H}=0 \mathrm{and} ∆\mathrm{U}=0$

4. $∆\mathrm{H}=0 \mathrm{and} ∆\mathrm{U}>0$

The incorrect statement(s) among the following statements is/are -

1. (i), (iv)
2. (ii), (iv)
3. (iii), (iv)
4. (i), (iii)

In an exothermic reaction, heat is evolved, and the system loses heat to the surrounding. The correct choice among the following for such a system are-

(a) q_p will be negative

(b) ${∆}_{\mathrm{r}}\mathrm{H}$ will be negative

(c) q_p will be positive

(d) ${∆}_{\mathrm{r}}\mathrm{H}$ will be positive

1. (a, b)

2. (b, c)

3. (c, d)

4. (a, d)