Which of the following statement is are correct ?

Options

A. `S_2O-8^(2-)` oxidises `Ag^(+)` in presence of pyridine and give red colour compound
B. `MnO_4^(2-)` disproportionates to yield `MnO_4^(-)` and `MnO_2` in presence of `H^+` ions
C. In `Cr_2O_7^(2-)` each Cr is linked to four oxygen atoms
D. `Ti^(2+)` is coloured while `Ti^(4+)` is colourless in aqueous solution

Explanation

To determine which statements are correct, we will analyze each statement one by one based on the information provided in the video transcript.

### Step-by-Step Solution:

1. **Statement 1: H2O8-2 oxidizes Ag+1 in presence of pyridine and gives a red color compound.**
- The reaction can be represented as:
\[ S_2O_8^{2-} + 2Ag^+ \rightarrow 2SO_4^{2-} + 2Ag^{2+} \]
- The Ag²⁺ ion forms a complex with pyridine, denoted as \( Ag(PY)_4^{2+} \), which is red in color.
- **Conclusion:** This statement is **correct**.

2. **Statement 2: MnO4-2 disproportionates to yield MnO4-1 and MnO2 in presence of H+ ions.**
- The disproportionation reaction can be written as:
\[ MnO_4^{2-} + 4H^+ \rightarrow MnO_2 + 2MnO_4^{-} + 2H_2O \]
- In this reaction, manganese changes oxidation states: from +6 in \( MnO_4^{2-} \) to +4 in \( MnO_2 \) and +7 in \( MnO_4^{-} \).
- **Conclusion:** This statement is **correct**.

3. **Statement 3: In Cr2O7-2, each chromium is linked with 4 oxygen atoms.**
- The structure of \( Cr_2O_7^{2-} \) shows that each chromium atom is indeed bonded to 4 oxygen atoms.
- **Conclusion:** This statement is **correct**.

4. **Statement 4: Ti+2 is colored while Ti+4 is colorless in aqueous solution.**
- For \( Ti^{2+} \), the electronic configuration is \( [Ar] 4s^2 \), which has no unpaired electrons, thus it is colorless.
- For \( Ti^{4+} \), the configuration is \( [Ar] \), which also has no unpaired electrons, making it colorless as well.
- **Conclusion:** This statement is **incorrect**.

### Final Summary:
- **Correct Statements:** 1, 2, and 3.
- **Incorrect Statement:** 4.