Name two metals which react violently with cold water, Write any observation you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reactions?

Explanation

**Step-by-Step Solution:**

1. **Identify the Metals:**
The two metals that react violently with cold water are:
- Potassium (K)
- Sodium (Na)

2. **Observation When Dropped into Water:**
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