The absence of cobalt in minute quantities in human body causes what?

The perbromate ion was first synthesized in the 1960s in minute quantities by the radioactive decay of *SeO42-. How would you go about separating the BrO4- ion from the selenate ion?

The body is made up of many elements. The major element are oxygen, carbon, hydrogen, and nitrogen. They will be the "building blocks" for carbohydrates, proteins lipids, and DNA. Some elements are found in smaller quantities called "trace elements." Their presence is essential to bodily functioning. Identify at least 5 trace elements found in the human body its biological importance in the body, its dietary source, and what happens to the body if the element is deficient.