Which of the following statements is not correct?

Options

A. Copper liberates hydrogen from acids
B. In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine
C. `Mn^(3+)` and `Co^(3+)` are oxidising agents in aqueous solution
D. `Ti^(2+)` and `Cr^(2+)` are reducing agents in aqueous solution

Explanation

To solve the question "Which of the following statements is not correct?", we will analyze each statement provided in the options.

### Step-by-Step Solution:

1. **Analyze Statement 1: "Copper liberates hydrogen from acids."**
- Copper (Cu) is below hydrogen in the electrochemical series. This means that copper cannot displace hydrogen from acids. Therefore, this statement is incorrect.

2. **Analyze Statement 2: "In higher oxidation state, manganese forms stable compounds with oxygen and fluorine."**
- Manganese can exhibit a high oxidation state, such as +7 in Mn2O7. In this state, manganese forms stable compounds with highly electronegative elements like oxygen and fluorine. Thus, this statement is correct.

3. **Analyze Statement 3: "Mn +3 and Co +3 are oxidizing agents."**
- In the +3 oxidation state, manganese (Mn) has the electronic configuration of 3D4, and cobalt (Co) has 3D6. Both can gain electrons, which means they can act as oxidizing agents. Therefore, this statement is correct.

4. **Analyze Statement 4: "Titanium in +2 state and chromium are reducing agents in aqueous solution."**
- Titanium (Ti) in the +2 state has the configuration of 3D2, and chromium (Cr) in the +2 state has 3D4. Both still have electrons that they can lose, which allows them to act as reducing agents. Thus, this statement is also correct.

### Conclusion:
After analyzing all the statements, we find that the first statement is the only incorrect one. Therefore, the answer to the question is:

**Option 1: Copper liberates hydrogen from acids (is not correct).**