Which of the following are physical changes and which are chemical changes ?
Burning of incense stick

Explanation

**Step-by-Step Solution:**

1. **Understanding Physical and Chemical Changes:**
- A physical change involves a change in the physical state or appearance of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.
- A chemical change, on the other hand, results in the formation of new substances with different chemical properties. This often involves a reaction where the original substances are transformed into new products.

2. **Analyzing the Burning of an Incense Stick:**
- When an incense stick is burned, it undergoes a process where it reacts with oxygen in the air. This reaction produces new substances such as ash and smoke.
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