Question

A metallic oxide contain 40%oxygen if the metal is divalent find atomic weight of metal?

Answer 1

Here you go my friend the answer is

Assume the oxide has the formula MO. Let the atomic weight of M be x Then

16/x+16=40/100

Simplifying and solving for x yields

x=24

Thus the metal is magnesium and the equivalent weight is 12.

My problem is, how can we assume that the metallic oxide has the formula MO? For all we know, the metallic oxide may be M2O or M2O3. In fact, if we assume the latter formula we get

48/2x+48=40/100

giving

x=72