What type of semiconductor is obtained by doping $Si$ with $B$ $(Al, Ga)$?

Explain the structure of diamond and graphite.

Classify each of the following solids as ionic,metallic,molecular,network (covalent) or amorphous.
$(i)$ Tetra phosphorus decoxide $(P_{4}O_{10})$ $(ii)$ Ammonium phosphate $(NH_{4})_{3}PO_{4}$
$(iii)$ $SiC$ $(iv)$ $I_{2}$ $(v)$ $P_{4}$ $(vi)$ Plastic $(vii)$ Graphite $(viii)$ Brass $(ix)$ $Rb$ $(x)$ $LiBr$ $(xi)$ $Si$

Solid methane is

Which of the following is not a characteristic of a crystalline solid?

Graphite and Cinnabar are examples of $.......$ and $.......$ crystal systems,respectively.