Question

What is the oxidation state of As in H\(_3\)AsO\(_4\)?

• A. \( +3 \)
• B. \( +5 \)
• C. \( -3 \)
• D. \( -1 \)

Hint:

To determine the oxidation state of an element in a compound, use the known oxidation states of other elements in the compound and solve the equation.

Answer 1

The Correct Option is B

Step 1: Understanding oxidation states.
In \( \text{H}_3\text{AsO}_4 \), hydrogen has an oxidation state of \( +1 \) and oxygen has an oxidation state of \( -2 \). The total charge of the molecule is zero. Using this information, we calculate the oxidation state of As.

Step 2: Setting up the equation.
Let the oxidation state of As be \( x \). The equation for the sum of oxidation states is: \[ 3(+1) + x + 4(-2) = 0 \] Solving for \( x \), we get: \[ 3 + x - 8 = 0 \implies x = +5 \]
Step 3: Conclusion.
The correct answer is (B) \( +5 \), as calculated.