Identify the extensive property amongst the following.

What will be the $\Delta U$ value,when one mole of oxygen $(O_2)$ is heated from $-20^{\circ} C$ to $40^{\circ} C$ at constant volume (in $J$)? (Molar heat capacity for oxygen $\simeq 20.8 \ J \ mol^{-1} \ K^{-1}$)

What is heat capacity?

The correct order of molar heat capacities measured at $298 \ K$ and $1 \ bar$ is:

For a reaction $H_{2(g)} + \frac{1}{2}O_{2(g)} \longrightarrow H_2O_{(l)}$; $\Delta C_p = 32 \ J \ K^{-1}$,$\Delta H$ at $27 \ ^oC = -285.8 \ kJ \ mol^{-1}$. What will be the value of $\Delta H$ at $127 \ ^oC$ in $kJ \ mol^{-1}$?

Explain Heat Capacity.