What weight of `KmNO_4` is required to react completely with `500mL` of 0.4 M Cus in acidic medium?

Explanation

To find the weight of KMnO4 required to react completely with 500 mL of 0.4 M CuS in acidic medium, we can follow these steps:

### Step 1: Write the balanced chemical reaction
In acidic medium, KMnO4 acts as an oxidizing agent and is reduced from MnO4^- (oxidation state +7) to Mn^2+ (oxidation state +2). The reaction involving CuS can be represented as follows:

\[ \text{CuS} + \text{KMnO}_4 \rightarrow \text{Cu}^{2+} + \text{SO}_2 + \text{Mn}^{2+} \]

### Step 2: Determine the number of moles of CuS
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