With which of the following cations , alizarin will impart a rose red colour on the fabric?

Options

A. `Fe^(3+)`
B. `Cr^(3+)`
C. `Ba^(+2)`
D. `Al^(+3)`

Answer

To determine with which cation alizarin will impart a rose red color on fabric, we can follow these steps:

### Step 1: Understand Alizarin
Alizarin is a natural red dye with the chemical formula C14H8O4. It is derived from the roots of the madder plant and is known for its ability to color fabrics.

**Hint:** Alizarin is a dye, and understanding its chemical structure and properties is crucial for knowing how it interacts with different cations.

### Step 2: Identify the Role of Cations
Cations can act as mordants, which are substances that help fix dyes onto fabrics. A mordant forms a coordination complex with the dye and the fabric, enhancing the dye's adherence and color intensity.

**Hint:** Mordants are essential in dyeing processes, as they improve the bond between the dye and the fabric.

### Step 3: Analyze the Given Cations
The options provided are:
- Fe³⁺ (Iron)
- Cr³⁺ (Chromium)
- Ba²⁺ (Barium)
- Al³⁺ (Aluminum)

We need to determine which of these cations can effectively act as a mordant for alizarin.

**Hint:** Consider the common cations used in dyeing processes and their properties.

### Step 4: Determine the Correct Cation
Alizarin specifically forms a complex with Al³⁺ ions. When alizarin binds to the cellulose in the fabric through the Al³⁺ cation, it produces a rose red color. This is due to the specific interaction between alizarin and Al³⁺, which stabilizes the dye on the fabric.

**Hint:** Look for the cation that is known to form stable complexes with organic dyes, particularly with alizarin.

### Step 5: Conclusion
Based on the analysis, the correct answer is **Al³⁺ (Aluminum)**, as it is the cation that will impart a rose red color to the fabric when combined with alizarin.

**Final Answer:** Al³⁺ (Aluminum)