Choose the correct statement:

Options

A. 1 " mol of "`MnO_(4)^(ɵ)` ion can oxidise 5 " mol of "`Fe^(2+)` ion in acidic medium.
B. 1 " mol of "`Cr_(2)O_(7)^(2-)` ion can oxidise 6 " mol of "`Fe^(2+)` ion in acidic medium.
C. 1 " mol of "`Cu_(2)S` can be oxidised by 1.6 mole of `MnO_(4)^(ɵ)` ion in acidic medium.
D. 1 " mol of "CuS can be oxidised by 1 " mol of "`Cr_(2)O_(7)^(2-)` ion in acidic medium.

Explanation

To solve the question, we need to analyze each statement regarding the behavior of permanganate ions (MnO4^-), dichromate ions (Cr2O7^2-), iron ions (Fe^2+), copper(I) sulfide (Cu2S), and copper(I) sulfide (CuS) in acidic medium.

### Step-by-step Solution:

1. **Analyze Statement A:**
- In acidic medium, 1 mole of permanganate ion (MnO4^-) gains 5 moles of electrons.
- 1 mole of Fe^2+ loses 1 mole of electron.
- Therefore, 1 mole of MnO4^- can oxidize 5 moles of Fe^2+.
- **Conclusion:** Statement A is true.

2. **Analyze Statement B:**
- In acidic medium, 1 mole of dichromate ion (Cr2O7^2-) gains 6 moles of electrons.
- 1 mole of Fe^2+ loses 1 mole of electron.
- Therefore, 1 mole of Cr2O7^2- can oxidize 6 moles of Fe^2+.
- **Conclusion:** Statement B is true.

3. **Analyze Statement C:**
- In acidic medium, 1 mole of permanganate ion (MnO4^-) gains 5 moles of electrons.
- 1 mole of Cu2S loses 2 moles of electrons.
- Since 1 mole of MnO4^- can oxidize 5 moles of Fe^2+, but Cu2S does not fit this ratio correctly, the statement is incorrect.
- **Conclusion:** Statement C is false.

4. **Analyze Statement D:**
- 1 mole of CuS can be oxidized by 1 mole of Cr2O7^2-.
- In acidic medium, 1 mole of Cr2O7^2- gains 6 moles of electrons.
- 1 mole of CuS loses 2 moles of electrons.
- The stoichiometry does not match, making this statement incorrect.
- **Conclusion:** Statement D is false.

5. **Final Conclusion:**
- The correct statements are A and B. Therefore, the answer to the question is that options A and B are correct.