A certain metal hydroxide, M(OH)2, contains 32.8% oxygen by mass. What is the identity of the metal M?
Answer: Suppose the molar mass of metal M is x. Thus,
By simple algebraic manipulation, we get
x = 63.56 g/mol
We then check which metal has the molar mass of 63.56 g/mol using a periodic table
which gives us the final answer which is Copper (Cu).