(a) What type of semiconductor is obtained when silicon is doped with boron?

(b) What type of magnetism is shown in the following alignment of magnetic moments?

(c) What type of point defect is produced when AgCl is doped with CdCl₂?

(a) When silicon is doped with boron, p-type semiconductor is obtained. This is because boron (has 3 valence electrons) belongs to Group 13 of the periodic table and when it is doped with silicon (has 4 valence electrons) a vacant space is created which is called a hole. The semiconductor thus produced is p-type.

(b)

When the magnetic moments are all aligned upwards in the same direction, ferromagnetism is shown.

(c) When AgCl is doped with CdCl₂, the doping leads to an impurity defect and vacancy defect in the crystal. Two Ag⁺ ions are replaced by one Cd²⁺ ion.

The Cd²⁺ ion occupies the site of one of the Ag⁺ ion and a cationic vacancy is created at the site of the other Ag⁺ ion.