Starts off getting the basic facts wrong. "Cadm
Post# of 22456
"Cadmium is an inorganic compound with red-black solid appearance and it is categorised as semiconductor of n-type."
Cadmium is not a compound and not a semiconductor, it is an element and its symbol is Cd.
"The chemical formula of cadmium is CdSe."
Se is the symbol for the element selenium. Combine the two elements and you get cadmium selenide, which has the chemical formula of CdSe, which is a compound and a semiconductor.