Two litres of an ideal gas at a pressure of 10 atm expands isothermally at 25 °C into a vacuum until its total volume is 10 litres. The amount of heat absorbed during expansion is-

1. 80 J

2. -80 J

3. Zero

4. 50 J

Two litres of an ideal gas at a pressure of 10 atm expands isothermally at 25 °C against a constant external pressure of 1 atm until its total volume is 10 litres. The amount of heat absorbed during expansion is-

1. 80 atm L

2. -80 atm L

3. -8 atm L

4. 8 atm L

.

Two litres of 1 mol an ideal gas at a pressure of 10 atm expands isothermally at 25 °C into a vacuum until its total volume is 10 litres. The amount of heat absorbed during expansion is:
(Given: log 5 = 0.699)

1. 51. 39 atm L

2. 39.36 atm L

3. 37. 34 atm ml

4. 26. 49 atm L

If water vapour is assumed to be a perfect gas, molar enthalpy change for vapourisation of 1 mol of water at 1 bar and 100°C is 41kJ mol^–1. The internal energy change, when 1 mol of water is vapourised at 1 bar pressure and 100°C is-

1. 35.5 kJ mol^–1

2. 37.9 kJ mol^–1

3.  41 kJ mol^–1

4. 44.2 kJ mol^–1

1g of graphite is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atmospheric pressure according to the equation

C (graphite) + O₂(g) → CO₂(g)

During the reaction, the temperature rises from 298 K to 299 K. If the heat capacity of the bomb calorimeter is 20.7kJ/K, the enthalpy change for the above reaction at 298 K and 1 atm is-

1. – 2.48 ×10² kJ mol^–1

2^. – 3.45 ×10² kJ mol^–1

3. – 1.65 ×10² kJ mol^–1

4. – 1.88 ×10² kJ mol^–1

A swimmer coming out from a pool is covered with a film of water weighing about 18g. The internal energy of vaporization at 298K. is-

∆_vap H^⊖ for water at 298K= 44.01kJ mol^–1

1. 38.63 kJ
2. 43.82 J
3. 41.53 kJ
4. 40.33 J
$\mathrm{}\mathrm{}$

Assuming the water vapour to be a perfect gas. When 1 mol of water at 100°C and 1 bar pressure is converted to ice at 0°C, the change in internal energy is-

(The enthalpy of fusion of ice = 6.00 kJ mol^-1 , heat capacity of water = 4.2 J/g°C)

1. 13.56 kJ mol^-1

2. -12.16 kJ mol^-1

3. -13.56 kJ mol^-1

4. 12.16 kJ mol^-1

The combustion of one mole of benzene takes place at 298 K and 1 atm. After combustion, CO₂(g) and H₂O (l)
are produced and 3267.0 kJ of heat is liberated.
The standard enthalpy of formation, ∆_fH^⊖ of benzene is-

Standard enthalpies of formation of CO₂(g) and ${\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)$ are –393.5 kJ mol–1 and – 285.83 kJ mol^–1 respectively

1. 54. 24 kJ mol^-1
2. 48. 51 kJ mol^-1
3. 66. 11 kJ mol^-1
4. 15. 21 kJ mol^-1
$\mathrm{}\mathrm{}{}^{\mathrm{}}$

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

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