Select correct statement(s).

Options

A. `MnO_(4)^(-)` is intensive pink colour due to d-d electron.
B. `Cu(I)` is diamagnetic while `Cu(II)` is paramagnetic .
C. `CrO_(3)` is amphoteric oxide.
D. `[Ti(H_(2)O)_(6)]^(3+)` and `[Sc(H_(2)O)_(6)]^(3+)` both are coloured in aqueous soloution.

Explanation

To solve the question of selecting the correct statements from the given options, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** MnO4- is intense pink color due to d-d transition of electron.

**Analysis:**
- Manganese in MnO4- is in the +7 oxidation state.
- The electronic configuration of Mn in this state is [Ar] 3d^0 4s^0, meaning there are no d-electrons present.
- Since there are no d-electrons, d-d transitions cannot occur.
- The pink color of MnO4- is due to ligand-to-metal charge transfer (LMCT), not d-d transitions.

**Conclusion:** This statement is **incorrect**.

### Step 2: Analyze the second statement
**Statement:** Cu+ is diamagnetic while Cu2+ is paramagnetic.

**Analysis:**
- For Cu+ (cuprous ion), the electronic configuration is [Ar] 3d^10 4s^0. All electrons are paired, making it **diamagnetic**.
- For Cu2+ (cupric ion), the electronic configuration is [Ar] 3d^9 4s^0. There is one unpaired electron, making it **paramagnetic**.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze the third statement
**Statement:** CrO3 is amphoteric oxide.

**Analysis:**
- CrO3 is not amphoteric; it is an acidic oxide.
- When water is added to CrO3, it forms H2CrO4 (chromic acid), which indicates that it behaves as an acid, not as an amphoteric oxide.

**Conclusion:** This statement is **incorrect**.

### Step 4: Analyze the fourth statement
**Statement:** Titanium and scandium complexes are colored in aqueous solution.

**Analysis:**
- For Ti^3+ (titanium in +3 oxidation state), the electronic configuration is [Ar] 3d^1. There is one unpaired electron, which allows for d-d transitions and thus color.
- For Sc^3+ (scandium in +3 oxidation state), the electronic configuration is [Ar] 3d^0. There are no unpaired electrons, so it does not show color in solution.

**Conclusion:** This statement is **incorrect**.

### Final Conclusion
The only correct statement among the four provided is the second one:
- **Cu+ is diamagnetic while Cu2+ is paramagnetic.**