Choose the correct statement :

Options

A. 1 mole of `MnO_4^(-)` ion can oxidised 5 moles of `Fe^2+` ion in acidic medium
B. 1 mole of `Cr_2O_7^2-` ion can oxidised 6 moles of `Fe^2+` ion in acidic medium
C. 1 mole of `Cu_2S` ion can oxidised 1.6 moles of `MnO_4^(-)` ion in acidic medium
D. 1 mole of `Cu_2S` ion can oxidised by 1.33 moles of `Cr_2O_7^2-` ion in acidic medium

Explanation

To solve the question, we need to analyze each statement regarding the oxidation reactions involving the given ions in acidic medium. Let's evaluate each statement step by step.

### Step 1: Analyze the first statement
**Statement 1**: 1 mole of MnO4- ion can oxidize 5 moles of Fe2+ ion in acidic medium.

- **Reaction**: MnO4- + 8H+ + 5Fe2+ → Mn2+ + 4H2O + 5Fe3+
- **Oxidation States**:
- Mn changes from +7 in MnO4- to +2 in Mn2+ (a change of 5 electrons).
- Fe changes from +2 in Fe2+ to +3 in Fe3+ (a change of 1 electron).

Since 1 mole of MnO4- can oxidize 5 moles of Fe2+, this statement is **true**.

### Step 2: Analyze the second statement
**Statement 2**: 1 mole of Cr2O7^2- ion can oxidize 6 moles of Fe2+ ion in acidic medium.

- **Reaction**: Cr2O7^2- + 14H+ + 6Fe2+ → 2Cr3+ + 7H2O + 6Fe3+
- **Oxidation States**:
- Cr changes from +6 in Cr2O7^2- to +3 in Cr3+ (a change of 3 electrons per Cr atom).
- For 2 Cr atoms, the total change is 6 electrons.

Since 1 mole of Cr2O7^2- can oxidize 6 moles of Fe2+, this statement is **true**.

### Step 3: Analyze the third statement
**Statement 3**: 1 mole of Cu2S can oxidize 1.6 moles of MnO4- in acidic medium.

- **Reaction**: 5Cu2S + 2MnO4- + 16H+ → 10Cu2+ + 2Mn2+ + 8H2O
- **Oxidation States**:
- Mn changes from +7 in MnO4- to +2 in Mn2+ (5 electrons).
- Cu changes from -2 in Cu2S to +2 in Cu2+ (a change of 2 electrons per Cu atom).

The balanced equation shows that 5 moles of Cu2S react with 2 moles of MnO4-. Therefore, 1 mole of Cu2S can oxidize 0.4 moles of MnO4-, not 1.6 moles. Thus, this statement is **false**.

### Step 4: Analyze the fourth statement
**Statement 4**: 1 mole of Cu2S can oxidize 1.33 moles of Cr2O7^2- in acidic medium.

- **Reaction**: 6Cu2S + 2Cr2O7^2- + 16H+ → 12Cu2+ + 4Cr3+ + 8H2O
- **Oxidation States**:
- Cr changes from +6 in Cr2O7^2- to +3 in Cr3+ (3 electrons per Cr atom).

The balanced equation shows that 6 moles of Cu2S react with 2 moles of Cr2O7^2-. Therefore, 1 mole of Cu2S can oxidize 1/3 moles of Cr2O7^2-, not 1.33 moles. Thus, this statement is **false**.

### Conclusion
The correct statements are:
- **Statement 1**: True
- **Statement 2**: True
- **Statement 3**: False
- **Statement 4**: False

Thus, the correct answer is that **only statements 1 and 2 are true**.

### Summary of Correct Statements
- **Correct Statements**: 1 and 2 are correct.