A boy accidently splashes a few drops of `conc. H_2 SO_4` on his cotton shirt and splashed part blackens and holes appears. This is because the sulphuric acid

Options

A. Heats up the cotton so that it burns
B. Dehydrates the cotton
C. Causes the cotton to react with oxygen in air
D. Removes the elements of water from cotton.

Explanation

To understand why concentrated sulfuric acid (H₂SO₄) causes blackening and holes in a cotton shirt, we can break down the process step by step:

### Step-by-Step Solution:

1. **Nature of Concentrated Sulfuric Acid**: Concentrated sulfuric acid is known to be a strong dehydrating agent. This means it has a strong tendency to remove water (H₂O) from substances it comes in contact with.

**Hint**: Remember that dehydrating agents are substances that can remove water from other compounds.

2. **Composition of Cotton**: Cotton is primarily composed of cellulose, which is a carbohydrate made up of carbon (C), hydrogen (H), and oxygen (O) atoms. The chemical formula for cellulose can be represented as (C₆H₁₀O₅)n, indicating that it contains water in its structure.

**Hint**: Consider the molecular structure of organic compounds like cellulose and how they contain water.

3. **Reaction with Sulfuric Acid**: When concentrated sulfuric acid comes into contact with cotton, it starts to dehydrate the cellulose. This means it removes the water molecules from the cellulose structure.

**Hint**: Think about how dehydration affects the physical and chemical properties of a substance.

4. **Formation of Carbon**: As sulfuric acid continues to dehydrate the cotton, it breaks down the cellulose, leading to the formation of carbon. This process can cause the affected area to turn black due to the presence of carbon.

**Hint**: Consider the chemical changes that occur when organic materials are dehydrated.

5. **Creation of Holes**: The removal of water and the breakdown of the cellulose structure can lead to the weakening of the fabric. As the cellulose is destroyed, it can result in the formation of holes in the fabric.

**Hint**: Reflect on how structural integrity is compromised when a material undergoes chemical degradation.

6. **Conclusion**: Therefore, the blackening and the appearance of holes in the cotton shirt are primarily due to the dehydrating action of concentrated sulfuric acid, which removes water from the cellulose and causes it to break down into carbon and other byproducts.

**Hint**: Summarize the overall process: dehydration leads to carbon formation and structural damage.

### Final Answer:
The concentrated sulfuric acid causes the cotton shirt to blacken and develop holes because it acts as a dehydrating agent, removing water from the cellulose in the cotton and leading to its degradation.