Aluminium vessels should not be washed with materials containing washing soda because :

Options

A. Washing soda reacts with aluminium to form soluble aluminate.
B. Washing soda is expensive.
C. Washing soda is easily decompsed.
D. Washing soda reacts with aluminium to form insoluble aluminium oxide.

Answer

### Step-by-Step Solution

1. **Identify the Composition of Washing Soda**:
- Washing soda is chemically known as sodium carbonate (Na2CO3).

2. **Understand the Reaction of Washing Soda with Water**:
- When washing soda is dissolved in water, it dissociates to form sodium hydroxide (NaOH) and carbon dioxide (CO2). The reaction can be represented as:
\[ \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{CO}_2 \]

3. **Aluminium's Reaction with Water**:
- Under normal conditions, aluminium does not react with water because it forms a protective layer of aluminium hydroxide (Al(OH)3) that prevents further reaction.

4. **Effect of Sodium Hydroxide on Aluminium**:
- When sodium hydroxide (from washing soda) is introduced, it disrupts the protective layer of aluminium hydroxide. This allows aluminium to react with sodium hydroxide, leading to the formation of soluble aluminate ions:
\[ \text{Al} + \text{NaOH} + \text{H}_2\text{O} \rightarrow \text{Na}^+ + \text{Al(OH)}_4^- \]

5. **Conclusion**:
- The reaction of washing soda with aluminium leads to the formation of soluble aluminate, which can cause the concentration of aluminium to decrease. This is why aluminium vessels should not be washed with materials containing washing soda.

6. **Final Answer**:
- The correct reason why aluminium vessels should not be washed with washing soda is: **Washing soda reacts with aluminium to form soluble aluminate.**