Which of these is not a violation of conservation of mass?

Options

A. When petrol is combusted in a vessel, finally the vessel is empty
B. When a piece of camphor is left standing in a dish, after a long time the dish is empty
C. When a bottle of chloroform is left open, after a short time the bottle has nothing in it.
D. None of the above choices is a violation of the law.

Answer

To determine which of the given scenarios is not a violation of the conservation of mass, we need to analyze each option based on the law of conservation of mass. The law states that mass cannot be created or destroyed in a chemical reaction or physical transformation; it can only change forms.

### Step-by-Step Solution:

1. **Understanding the Law of Conservation of Mass**:
- The law states that in a closed system, the total mass of reactants must equal the total mass of products. This means that during any chemical reaction or physical change, mass is conserved.

2. **Analyzing the Scenarios**:
- **Scenario 1: Combustion of Petrol**:
- When petrol burns, it reacts with oxygen to produce carbon dioxide and water. Although the vessel may appear empty after combustion, the mass is not lost; it is converted to gaseous products (CO2 and H2O) and energy. Thus, this scenario does not violate the conservation of mass.

- **Scenario 2: Sublimation of Camphor**:
- When camphor is left in an open dish, it sublimates directly into vapor. The mass of camphor is converted into gaseous form, which may disperse into the air. However, the total mass of camphor is still conserved; it has merely changed states. Therefore, this scenario also does not violate the conservation of mass.

- **Scenario 3: Evaporation of Chloroform**:
- Similar to camphor, when chloroform is left open, it evaporates into the atmosphere. The mass of chloroform is converted into vapor, and while it may seem that the mass is lost, it is still present in the gaseous state. Hence, this scenario does not violate the conservation of mass.

3. **Conclusion**:
- Since all three scenarios involve processes where mass is conserved (it changes form but is not lost), none of them violate the law of conservation of mass. Therefore, the correct answer is:
- **Option 4: None of the above choices is a violation of the law.**