Question

Oxidation numbers of oxygen in H_2O_2 and H_2O:

• A. –1 and –2
• B. –2 and –1
• C. –2 and –2
• D. 0 and –2

Hint:

In H\(_2\)O\(_2\), oxygen has an oxidation number of –1, and in H\(_2\)O, oxygen has an oxidation number of –2.

Answer 1

The Correct Option is A

Step 1: Understanding the oxidation state of oxygen in H\(_2\)O\(_2\).
In hydrogen peroxide (H\(_2\)O\(_2\)), oxygen has an oxidation number of –1, because the total oxidation state of hydrogen is +2 and the molecule is neutral.
Step 2: Understanding the oxidation state of oxygen in H\(_2\)O.
In water (H\(_2\)O), oxygen has an oxidation number of –2, as the total oxidation state of hydrogen is +2 and the molecule is neutral.
Step 3: Conclusion.
Thus, the oxidation numbers of oxygen in H\(_2\)O\(_2\) and H\(_2\)O are –1 and –2, respectively, which corresponds to option (A).

Answer 2

Step 1: In hydrogen peroxide (H₂O₂), the two hydrogens together contribute +2, and since the molecule is neutral, the two oxygens together must be −2 — so each oxygen is −1.

Step 2: In water (H₂O), the two hydrogens again contribute +2, so oxygen balances at −2.

Step 3: So the oxidation numbers of oxygen are −1 in H₂O₂ and −2 in H₂O — option (A).

Answer 3

Recognizing the compound class: H\(_2\)O\(_2\) is a peroxide, and by definition every oxygen in a peroxide's oxygen-oxygen linkage is assigned an oxidation number of -1, because each oxygen shares its extra bond only with the other oxygen atom. Ordinary water has no such oxygen-oxygen bond, so its oxygen keeps the usual -2 seen in almost all other oxygen compounds. That gives -1 for H\(_2\)O\(_2\) and -2 for H\(_2\)O, option (A).