Combustion Products of Sodium Metal in Excess Air

To determine the compound(s) formed upon combustion of sodium metal in excess air, we analyze the reaction behavior of alkali metals with oxygen:

1. Reactivity of Alkali Metals with Oxygen:
   • Lithium ($\text{Li}$): Due to its small size and high lattice energy with the oxide ion, it burns predominantly to form the normal oxide (monoxide), $\text{Li}_2\text{O}$.
   • Sodium ($\text{Na}$): Being larger in size, sodium predominantly forms sodium peroxide ($\text{Na}_2\text{O}_2$) as the major product upon combustion in an excess of air or oxygen:
     $2\text{Na} + \text{O}_2 \xrightarrow{\Delta} \text{Na}_2\text{O}_2 \quad (\text{major product})$
     Along with the peroxide, a small amount of sodium monoxide ($\text{Na}_2\text{O}$) is also formed:
     $4\text{Na} + \text{O}_2 \xrightarrow{\Delta} 2\text{Na}_2\text{O} \quad (\text{minor product})$
   • Potassium ($\text{K}$), Rubidium ($\text{Rb}$), and Caesium ($\text{Cs}$): Due to their large ionic radii and the lower charge density, they stabilize the larger superoxide ion ($\text{O}_2^-$) and form superoxides ($\text{MO}_2$). Sodium superoxide ($\text{NaO}_2$) is generally not formed under normal atmospheric combustion conditions and requires elevated oxygen pressures.
   • Sodium hydroxide ($\text{NaOH}$): It is formed upon the reaction of sodium or its oxides with moisture, not as a direct combustion product with dry excess air.

Therefore, the compounds formed upon combustion of sodium metal in excess air are sodium peroxide ($\text{Na}_2\text{O}_2$) and sodium monoxide ($\text{Na}_2\text{O}$).

Thus, the correct options are A and B.