Answer:
Tantalium (Ta) is found uncombined in nature. It is found in coloumbite-tantalite. Tantalium also comes as a result of Mining. It is separated from others by Electrolysis.
Osmium comes when there is a reaction of Nickel refining as by-product. It is rare element which is found naturally as a free element. It is also found naturally in Alloys with copper and nickel.
Rhodium is obtained as the by-product of Copper as well as Nickel refining.