Vacuum toilets are usually used in :

Options

A. superfast trains
B. cinema halls
C. aeroplanes
D. large ships

Answer

**Step-by-Step Solution:**

1. **Understanding Vacuum Toilets**: Vacuum toilets are a type of flush toilet that operates using a negative pressure system. Instead of using a large amount of water to flush waste, they use suction to remove feces and urine.

2. **Identifying Usage Locations**: The question asks where vacuum toilets are usually used. We need to consider environments where water usage is limited and efficient waste removal is necessary.

3. **Evaluating Options**: The options provided are:
- 1) Super fast trains
- 2) Cinema halls
- 3) Aeroplanes
- 4) Large ships

4. **Analyzing Each Option**:
- **Super fast trains**: While they may use efficient toilets, they typically have more water available than aeroplanes.
- **Cinema halls**: These usually have standard toilets that do not require vacuum systems.
- **Aeroplanes**: These have very limited water supply and require efficient waste removal systems, making vacuum toilets ideal.
- **Large ships**: They may have various types of toilets, but they often have more water available than aeroplanes.

5. **Conclusion**: Based on the analysis, vacuum toilets are most commonly used in aeroplanes due to their need for minimal water and efficient waste removal.

**Final Answer**: Vacuum toilets are usually used in aeroplanes (Option 3).

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