Which of the following statement is incorrect

Options

A. In equilibrium mixture of ice and water kept in perfectly insulated flask, mass of ice does not change with time
B. The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate
C. On addition of catalyst the equilibrium constant value is not affected
D. Equilibrium constant for a reaction with negative `DeltaH` value decreases as the temperature increases

Explanation

To determine which statement is incorrect among the given options, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement 1:** "The equilibrium mixture of ice and water kept in a perfectly insulated glass. Mass of ice does not change with time."

- **Analysis:** In a perfectly insulated system, there is no exchange of heat or mass with the surroundings. Since the system is at equilibrium, the mass of ice will remain constant over time. Therefore, this statement is **true**.

### Step 2: Analyze the second statement
**Statement 2:** "The intensity of the red color increases when oxalic acid is added to a significant amount of iron (III) in potassium phosphate."

- **Analysis:** When oxalic acid is added to iron (III) ions (Fe³⁺), it forms a complex that reduces the concentration of free Fe³⁺ ions in solution. This shift in equilibrium will lead to a decrease in the intensity of the red color associated with the Fe(SCN)²⁺ complex. Therefore, this statement is **false**.

### Step 3: Analyze the third statement
**Statement 3:** "On addition of a catalyst, the equilibrium constant value is not affected."

- **Analysis:** A catalyst speeds up the rate of both the forward and reverse reactions equally, but it does not change the position of equilibrium or the equilibrium constant. Therefore, this statement is **true**.

### Step 4: Analyze the fourth statement
**Statement 4:** "Equilibrium constant for a reaction with delta H value negative decreases as the temperature increases."

- **Analysis:** For an exothermic reaction (negative ΔH), increasing the temperature shifts the equilibrium position to favor the reactants (Le Chatelier's principle). As a result, the equilibrium constant decreases with an increase in temperature. Therefore, this statement is **true**.

### Conclusion
After analyzing all statements, the incorrect statement is **Statement 2**.

### Final Answer
The incorrect statement is: **"The intensity of the red color increases when oxalic acid is added to a significant amount of iron (III) in potassium phosphate."**

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