A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns red. On rinsing the shirt with planty of water, the red stain turns yellow again.
Name it synthetic indicator which will give pink colour with soap solution.

Explanation

To solve the question, let's break it down step by step:

### Step 1: Identify the yellow stain
The yellow stain on the white shirt is due to turmeric, which is commonly used in cooking. Turmeric acts as a natural pH indicator.

**Hint:** Think about common kitchen ingredients that can change color based on pH.

### Step 2: Understand the reaction with soap
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