An ore on treatment with dilute hydrochloric acid gives a smell like that of rotten eggs: What type of ore is this? How can it be concentrated? How can the metal be obtained from the concentrated ore?

Explanation

The gas which smells like that ofrotten eggs is `H_2S` (Hydrogen sulphide). The metal is obtained from the concentrated ore in the following two steps:
(i) Roasting, i.e., heating the ore strongly in the presence of air. The metal sulphide is converted into metal oxide with evolution of sulphur dioxide gas.
`"Metal sulphide" + O_2 overset("Roasting")to" Metal oxide "+SO_2 uarr`
(ii) Reduction with carbon. The metal oxide is heated with carbon which then is reduced to free metal.
`"Metal oxide + Carbon" rarr" Metal + Carbon monoxide"`