What is the two-dimensional coordination number of a molecule in square close-packed layer?

Explanation

To determine the two-dimensional coordination number of a molecule in a square close-packed layer, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Arrangement**: In a square close-packed layer, the atoms are arranged in a two-dimensional square grid. Each atom is positioned at the corners of squares formed by neighboring atoms.

2. **Identify the Nearest Neighbors**: For any given atom in this arrangement, we need to identify its nearest neighboring atoms. In a square close-packed structure, each atom has four nearest neighbors.

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