Identify the physical and chemical changes among the following

Options

A. Preparation of liquefied petroleum gas
B. Usage of liquefied petroleum gas
C. Formation of manure
D. Formation of glass

Explanation

To identify the physical and chemical changes among the given processes, we will analyze each process step by step.

### Step-by-Step Solution:

1. **Understanding Physical Changes**:
- Physical changes are changes that do not alter the chemical composition of a substance. They can involve changes in state (solid, liquid, gas) but the substance remains the same chemically. These changes are often reversible.

2. **Understanding Chemical Changes**:
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