Two mercury drops each of radius r merge to form a bigger drop. Calculate the surface energy released.

Explanation

To solve the problem of calculating the surface energy released when two mercury drops of radius \( r \) merge to form a bigger drop, we can follow these steps:

### Step 1: Calculate the Surface Area of the Small Drops
Each small mercury drop has a radius \( r \). The surface area \( A \) of a single drop is given by the formula:
\[ A = 4\pi r^2 \]
Since there are two identical drops, the total surface area \( A_{\text{total}} \) of the two small drops before merging is:
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