How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle? Why can the same process not be applied for them? Name the process used for extraction of these metals.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Reactivity Series**:
- The reactivity series is a list of metals arranged in order of decreasing reactivity. Metals at the top of the series are more reactive than those in the middle.

2. **Extraction of Highly Reactive Metals**:
- Metals that are high up in the reactivity series (like potassium, sodium, and calcium) typically exist in nature as stable oxides. These oxides are not easily reduced by carbon due to their stability.
- Therefore, the extraction method used for these metals is **electrolytic reduction**. In this process, the metal oxides are melted, and electrolysis is performed to separate the metal from the oxide. The metal is deposited at the cathode during the electrolysis.
...