Caro's and Marshall'a acid does not react with

Options

A. S
B. `KMnO_4`
C. `KI`
D. `H_2 O`

Explanation

To determine which substances Caro's acid (H2SO5) and Marshall's acid (H2SO8) do not react with, we need to analyze their properties and the properties of the substances listed in the question.

### Step 1: Identify the nature of Caro's and Marshall's acids
- Caro's acid (H2SO5) and Marshall's acid (H2SO8) are both strong oxidizing agents. This is due to the high oxidation state of sulfur in these compounds, which is +6.

**Hint:** Strong oxidizing agents typically do not react with other strong oxidizing agents.

### Step 2: Analyze the oxidation states
- In Caro's acid and Marshall's acid, sulfur has an oxidation state of +6.
- KMnO4 (Potassium permanganate) contains manganese in the +7 oxidation state, which is a higher oxidation state than +6.

**Hint:** Compare the oxidation states of the elements involved to determine reactivity.

### Step 3: Determine reactivity with other substances
- **Sulfur**: Can react with Caro's and Marshall's acids.
- **KMnO4**: Cannot react with Caro's and Marshall's acids because both are strong oxidizing agents and cannot oxidize each other.
- **KI (Potassium iodide)**: Can react with Caro's and Marshall's acids.
- **H2O (Water)**: Can also react with Caro's and Marshall's acids.

**Hint:** Identify which substances are strong oxidizers and which are not.

### Step 4: Conclusion
- The substance that does not react with Caro's and Marshall's acids is **KMnO4**. This is because both Caro's and Marshall's acids are strong oxidizing agents, and KMnO4 is also a strong oxidizing agent, making them incompatible for a reaction.

**Final Answer:** Caro's and Marshall's acids do not react with **KMnO4**.