A sample of pure germanium has one impurity atom to atoms of germanium. We have to calculate the distance between impurity atoms.

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From the physical data of germanium we calculate the number of germanium atoms per cubic meter. The physical data for germanium are:

molar mass of germanium,

density of germanium,

Therefore, the number of germanium atoms per cubic meter is given by

It is given that a sample of pure germanium has one impurity atom to atoms of germanium. Therefore, the number of impurity atoms per cubic meter in that sample of germanium will be

.

Therefore, the average distance between impurity atoms will be