Question

What is the oxidation state of chromium in the compound \( \text{Cr}_2\text{O}_3 \)?

• A. +2
• B. +3
• C. +6
• D. +1

Hint:

In compounds, the sum of the oxidation states of all atoms must equal the charge on the molecule (zero for neutral compounds). Use this principle to find the oxidation state of elements.

Answer 1

The Correct Option is B

In \( \text{Cr}_2\text{O}_3 \), oxygen has an oxidation state of -2 (since oxygen typically has an oxidation state of -2). Let the oxidation state of chromium be \( x \). For the compound to be neutral, the sum of the oxidation states must be zero. The total oxidation state of the oxygen atoms is \( 3 \times (-2) = -6 \). Therefore, the total oxidation state of the two chromium atoms must be +6 to balance the -6 from the oxygen atoms. Since there are 2 chromium atoms, the oxidation state of each chromium atom is: \[ \frac{+6}{2} = +3 \] Thus, the oxidation state of chromium in \( \text{Cr}_2\text{O}_3 \) is +3.