Roasting of copper pyrites ores is for the following purposes
a) to burn off sulphur, arsenic, antimony etc. as oxides and convert all the iron and copper to their oxides b) to burn off arsenic, antimony etc. as oxides and burn off sulphur so that enough of it remains to combine with all the copper c) to burn off sulphur partially to leave enough to combine with arsenic, antimony etc. and to convert all the iron and copper to oxides d) to melt arsenic and antimony etc. and remove them by liquation and to burn off sulphur partially to leave enough to combine with copper and iron

answer:

like the alkali metals, the alkaline earth metals are so reactive that are never found in elemental form in nature. because form +2 ions that have very negative reduction potentials, large amounts of energy are needed to isolate them from their ores. four of the six group 2 elements—magnesium (mg), calcium (ca), strontium (sr), and barium (ba)—were first isolated in the early 19th century by sir humphry davy, using a technique similar to the one he used to obtain the first alkali metals. in contrast to the alkali metals, however, compounds of the alkaline earth metals had been recognized as unique for many centuries. in fact, the name alkali comes from the arabic al-qili, meaning “ashes,” were known to neutralize acids.