Question

In acid medium, dichromate oxidizes sulphite to sulphate. In this redox reaction, the oxidation state of sulphur changes from \(x\) to \(y\). What is the value of \(x + y\)?

• A. 8
• B. 6
• C. 10
• D. 12

Hint:

Always assign oxidation states using standard rules: Oxygen is typically -2, and the sum of oxidation numbers equals the charge on the ion. For redox questions, compare oxidation states to track electron transfer.

Answer 1

The Correct Option is C

Step 1: Identify oxidation states of sulphur in sulphite and sulphate.
In sulphite (SO\(_3^{2-}\)): \[ \text{Oxidation state of S} = x \Rightarrow x + 3(-2) = -2 \Rightarrow x = +4 \] In sulphate (SO\(_4^{2-}\)): \[ \text{Oxidation state of S} = y \Rightarrow y + 4(-2) = -2 \Rightarrow y = +6 \] Step 2: Calculate \(x + y\)
\[ x + y = 4 + 6 = 10 \]