Question

A certain protein was found to contain 0.818% manganese by mass. Determine the minimum molecular mass of the protein.

Answer 1

That's an interesting question to ask as minimum molecular mass is the important thing
As given inn the data the manganese present is equal to 0.818. That's mean hundred gram of protein will contain = 0.412 g of manganese 
and we know that molar mass of manganese is equal to 54.938 u
so  we will calculate that in 100 g we will have the 0.818/54.938 moles of manganese which will be equal to 0.0149 g moles of manganese.
and in totall 100 gram of protein 
1mole= 100/ 0.0149 = 6711 g/mol of protein minimum molecular mass