While performing a thermodynamics experiment, a student made the following observations.

HCl + NaOH $$\to$$ NaCl + H₂O $$\Delta$$H = $$-$$57.3 kJ mol^$$-$$1

CH₃COOH + NaOH $$\to$$ CH₃COONa + H₂O $$\Delta$$H = $$-$$55.3 kJ mol^$$-$$1

The enthalpy of ionization of CH₃COOH as calculated by the student is _____________ kJ mol^$$-$$1. (nearest integer)

The enthalpy of combustion of propane, graphite and dihydrogen at $$298 \mathrm{~K}$$ are $$-2220.0 \mathrm{~kJ} \mathrm{~mol}^{-1},-393.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$$ and $$-285.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$$ respectively. The magnitude of enthalpy of formation of propane $$\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)$$ is _______________ $$\mathrm{kJ} \,\mathrm{mol}^{-1}$$. (Nearest integer)

1.0 mol of monoatomic ideal gas is expanded from state 1 to state 2 as shown in the figure. The magnitude of the work done for the expansion of gas from state 1 to state 2 at 300 K is ____________ J. (Nearest integer)

(Given : R = 8.3 J K^$$-$$1 mol^$$-$$1, ln10 = 2.3, log2 = 0.30)

2.2 g of nitrous oxide (N₂O) gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1 mL to 167.75 mL. The change in internal energy of the process, $$\Delta$$U is '$$-$$x' J. The value of 'x' is ________. [nearest integer]

(Given : atomic mass of N = 14 g mol^$$-$$1 and of O = 16 g mol^$$-$$1. Molar heat capacity of N₂O is 100 J K^$$-$$1 mol^$$-$$1)