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 determine which statement is not correct among the given options, we will analyze each statement step by step.

### Step 1: Analyze Option 1
**Statement:** Copper liberates Hydrogen from Acids.

**Explanation:**
- Copper (Cu) has a standard electrode potential of +0.34 V.
- In the electrochemical series, metals that can liberate hydrogen from acids must have a more negative electrode potential than hydrogen (which is 0 V).
- Since copper is above hydrogen in the electrochemical series, it cannot displace hydrogen from acids.
- Therefore, this statement is **not correct**.

### Step 2: Analyze Option 2
**Statement:** In its higher oxidation state, manganese forms stable compounds with oxygen and fluorine.

**Explanation:**
- Manganese can exhibit multiple oxidation states, with +4 and +7 being common.
- In the +4 oxidation state, manganese forms stable compounds such as manganese dioxide (MnO2).
- In the +7 oxidation state, it forms potassium permanganate (KMnO4), which is also stable.
- Therefore, this statement is **correct**.

### Step 3: Analyze Option 3
**Statement:** Ti²⁺ and Cr²⁺ are reducing agents in aqueous solution.

**Explanation:**
- Titanium in the +2 oxidation state (Ti²⁺) and chromium in the +2 oxidation state (Cr²⁺) can act as reducing agents.
- They can donate electrons to other species, thus reducing them while being oxidized themselves.
- Therefore, this statement is **correct**.

### Conclusion
After analyzing all the options, we find that **Option 1** is the statement that is **not correct**.

### Final Answer
**Option 1 is not correct: Copper does not liberate hydrogen from acids.**

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