The empty space left between the spheres in close-packed structure is called voids. The decreasing order of the size of voids is

Options

A. cubic `gt` octahedral `gt` tetrahedral `gt` trigonal
B. octahedral `gt` tetrahedral `gt` trigonal `gt` cubic
C. tetrahedral `gt` trigonal `gt` cubic `gt` octahedral
D. trigonal `gt` cubic `gt` octahedral `gt` tetrahedral

Answer

To determine the decreasing order of the size of voids in a close-packed structure, we need to analyze the types of voids present and their respective sizes. The voids are categorized as follows:

1. **Cubic Voids**: These are the largest voids formed in a close-packed structure. In a cubic void, there are a total of 8 lattice points surrounding it. This makes it the largest type of void.

2. **Octahedral Voids**: These are the second largest voids. An octahedral void is surrounded by 6 lattice points. This makes it smaller than the cubic void but larger than the tetrahedral void.

3. **Tetrahedral Voids**: These voids are smaller than octahedral voids. A tetrahedral void is surrounded by 4 lattice points, making it smaller than the octahedral void.

4. **Trigonal Voids**: These are the smallest voids in a close-packed structure. A trigonal void is surrounded by 3 lattice points, making it the smallest type of void.

Now, we can summarize the sizes of the voids in decreasing order:

- **Cubic Voids** (largest)
- **Octahedral Voids**
- **Tetrahedral Voids**
- **Trigonal Voids** (smallest)

Thus, the decreasing order of the size of voids is:

**Cubic > Octahedral > Tetrahedral > Trigonal**