Fill in the blanks by choosing the appropriate word from those given in the brackets. (isotropic, anisotropic, 0.255–0.414, 0.414–0.732, unit cell AB AB, .... ABC ABC ..., ...., 52.4, 60.4, F-centres, V-centres, 4, 2, hexagonal close packing, square close packing, 6, 8 glass, plastics, lead zirconate, barium titanate)
In square close packing pattern of spheres of identical size in one layer, the coordination number of each sphere will be.....

Explanation

To solve the question, we need to determine the coordination number of spheres in a square close packing arrangement.

### Step-by-Step Solution:

1. **Understanding Square Close Packing**: In a square close packing arrangement, the spheres are arranged in layers where each sphere in one layer is directly above the spheres in the layer below. The arrangement is such that the spheres are aligned both horizontally and vertically.

2. **Visualizing the Arrangement**: Imagine two layers of spheres. The first layer can be labeled as A, and the second layer, which is directly above the first, is also labeled as A. This means that the spheres in the second layer are positioned directly above those in the first layer.

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