Which statement is correct?

Options

A. In SHE, the pressure of dihydrogen gas should be low and pH of solution should be zero.
B. in the reaction `H_(2)O_(2)+O_(3)to2H_(2)O+2O_(2),H_(2)O_(2)` is oxidised to `H_(2)O`.
C. The absolute value of electrode potential cannot be determined.
D. According to IUPAC conventions, the standard electrode potential pertains to oxidation reactions only.

Answer

To determine which statement is correct, we will analyze each option step by step.

### Step 1: Analyze the First Statement
**Statement:** In standard hydrogen electrode, the pressure of dihydrogen gas should be low and pH of solution should be zero.

**Analysis:**
- The standard hydrogen electrode (SHE) operates at a pressure of 1 atm for dihydrogen gas (H2), not low pressure.
- The pH of the solution in SHE is typically 0 when the concentration of H+ ions is 1 M. However, this is not a requirement for all conditions.
- Therefore, this statement is **incorrect**.

### Step 2: Analyze the Second Statement
**Statement:** In the reaction H2O2 + O3 → 2 H2O + 2 O2, H2O2 is oxidized to water.

**Analysis:**
- In this reaction, H2O2 (hydrogen peroxide) is converted to H2O (water).
- To determine if H2O2 is oxidized or reduced, we need to check the oxidation states:
- In H2O2, the oxidation state of oxygen is -1.
- In H2O, the oxidation state of oxygen is -2.
- Since the oxidation state of oxygen decreases from -1 to -2, H2O2 is being reduced, not oxidized.
- Therefore, this statement is **incorrect**.

### Step 3: Analyze the Third Statement
**Statement:** The absolute value of electrode potential can't be determined.

**Analysis:**
- The absolute value of electrode potential cannot be measured directly; it is determined relative to the standard hydrogen electrode.
- Thus, this statement is **correct**.

### Step 4: Analyze the Fourth Statement
**Statement:** According to IUPAC convention, the standard electrode potential pertains to oxidation reactions only.

**Analysis:**
- The standard electrode potential can pertain to both oxidation and reduction reactions.
- Therefore, this statement is **incorrect**.

### Conclusion
After analyzing all statements, the correct answer is:
**C: The absolute value of electrode potential can't be determined.**

---