How many moles of `K_2Cr_2O_7` all required to react completely with 2.5 " mol of "`Cu_2S` in acidic medium?

Explanation

To solve the problem of how many moles of \( K_2Cr_2O_7 \) are required to react completely with 2.5 moles of \( Cu_2S \) in acidic medium, we can follow these steps:

### Step 1: Write the balanced chemical equations
First, we need to identify the reactions involved. The oxidation of \( Cu_2S \) and the reduction of \( K_2Cr_2O_7 \) can be represented as follows:

1. **Oxidation of \( Cu_2S \)**:
\[
Cu_2S + 2H_2O \rightarrow 2Cu^{2+} + S + 2H^+ + 2e^-
...