When 600 mL of 0.2 M HNO₃ is mixed with $$400 \mathrm{~mL}$$ of 0.1 M NaOH solution in a flask, the rise in temperature of the flask is ___________ $$\times 10^{-2}{ }\,^{\circ} \mathrm{C}$$.

(Enthalpy of neutralisation $$=57 \mathrm{~kJ} \mathrm{~mol}^{-1}$$ and Specific heat of water $$=4.2 \,\mathrm{JK}^{-1} \mathrm{~g}^{-1}$$) (Neglect heat capacity of flask)

Among the following the number of state variables is ______________.

Internal energy (U)

Volume (V)

Heat (q)

Enthalpy (H)

A gas (Molar mass = 280 $$\mathrm{~g} \mathrm{~mol}^{-1}$$) was burnt in excess $$\mathrm{O}_{2}$$ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from $$298.0 \mathrm{~K}$$ to $$298.45$$ $$\mathrm{K}$$. If the heat capacity of calorimeter is $$2.5 \mathrm{~kJ} \mathrm{~K}^{-1}$$ and enthalpy of combustion of gas is $$9 \mathrm{~kJ} \mathrm{~mol}^{-1}$$ then amount of gas burnt is _____________ g. (Nearest Integer)

The molar heat capacity for an ideal gas at constant pressure is $$20.785 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$. The change in internal energy is $$5000 \mathrm{~J}$$ upon heating it from $$300 \mathrm{~K}$$ to $$500 \mathrm{~K}$$. The number of moles of the gas at constant volume is ____________. [Nearest integer] (Given: $$\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$)