Final answer:
The maximum size of an anion forming voids in the unit cell is approximately 100 pm, and the minimum size is equal to the cation size of 75 pm, making option B (Max: 125 pm, Min: 50 pm) the closest given choice.
Step-by-step explanation:
To determine the maximum and minimum sizes of the anions that form voids in the unit cell of an AB type solid with a cation radius of 75 pm, we look at the types of voids available. According to Figure 10.58, if the cations are fitting into octahedral holes, their radius is about 41.4 to 73.2% of the anion radius, and for cubic holes, it is about 73.2 to 100% of the anion radius.
For octahedral holes, since the cation radius is 75 pm, and it constitutes up to 73.2% of the anion radius, we calculate the maximum size of an anion as 75 pm / 0.732, which gives us approximately 102.5 pm. This means that choice C (100 pm) would be an appropriate approximation for the maximum size of an anion.
The minimum size is not precisely given, but if the cation were to occupy a cubic hole, it would take up to 100% of the anion radius, making the sizes equal; therefore, the minimum size of an anion that can form voids would be equal to the cation size of 75 pm.
With our calculations and the given options, the answer to the question about the sizes of the anions would be option B: Maximum: 125 pm, Minimum: 50 pm, though our calculation gives us an approximation of 100 pm for the maximum size.
Therefore answer is b. Maximum: 125 pm, Minimum: 50 pm.