Give suitable reasons for the following statements: The crystals of washing soda change to white powder on exposure to air.

Explanation

**Step-by-Step Solution:**

1. **Identify the Chemical Composition**: Washing soda is chemically known as sodium carbonate decahydrate, with the formula Na2CO3·10H2O. This indicates that each formula unit of washing soda contains 10 molecules of water of crystallization.

2. **Understand the Concept of Efflorescence**: Washing soda is classified as an efflorescent substance. Efflorescence refers to the process where a hydrated compound loses its water of crystallization when exposed to air.

3. **Exposure to Air**: When washing soda crystals are exposed to air, they undergo efflorescence. The surrounding air has a lower humidity level compared to the water content in the washing soda crystals.

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