Identify the pair of basic oxides from the following.

Oxides of metals are generally basic in nature, while oxides of non-metals are generally acidic or neutral.

$\text{CaO}$ and $\text{Na}_2\text{O}$ are oxides of an alkaline earth metal (Ca) and an alkali metal (Na) respectively. Both react with water to form strong bases ($\text{Ca(OH)}_2$ and $\text{NaOH}$). Hence, they are basic oxides.

$\text{SO}_2$ and $\text{Cl}_2\text{O}$ are non-metallic oxides and are acidic in nature.

$\text{BaO}$ is a basic oxide, but $\text{N}_2\text{O}_5$ is an acidic oxide.

$\text{CO}$ and $\text{N}_2\text{O}$ are neutral oxides.

Answer: $\text{CaO}$ and $\text{Na}_2\text{O}$