(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? $\uparrow\;\uparrow\;\uparrow\;\uparrow\;\uparrow\;\uparrow$ (c) What type of point defect is produced when $\mathrm{AgCl}$ is doped with $\mathrm{CdCl}_2$ ?