Question

In which of the following compounds does the oxidation number of oxygen equal +2?

• A. \( F_2O \)
• B. \( Na_2O_2 \)
• C. \( K_2O \)
• D. \( O_3 \)

Hint:

The oxidation number of oxygen is typically -2, except in peroxides where it is -1, and in compounds with fluorine where it can be +2.

Answer 1

The Correct Option is B

In the compound \( Na_2O_2 \) (sodium peroxide), the oxidation number of oxygen is -1 in the peroxide ion (\( O_2^{2-} \)). However, in compounds like \( F_2O \), oxygen has an oxidation state of +2 (since fluorine is more electronegative). \( O_3 \) (ozone) has an oxidation state of 0 for oxygen. Thus, the correct compound where the oxidation number of oxygen is +2 is \( Na_2O_2 \).