IIT-JEE 2009 · Paper 1, Chemistry question 11

Burning sodium in excess air gives mainly sodium peroxide:
$$\ce{2Na + O2 -> Na2O2}.$$
Some $\ce{Na2O}$ also forms, which is why the key also accepts (A, B). Sodium does not form the superoxide on ordinary combustion (that is typical of K, Rb, Cs), and NaOH needs water.

(A) (key: A, or A and B)