If the total number of electrons in the ion [M (H2O) 4] +2 is equal to 50
Whish is the atomic number of M?
2 electrons for the two H atoms, +8 electrons for the O atom = 10 for one H2O molecules. That x 4 = 40 for the 4 H2O molecules. That means M^2+ must be 50-40= 10.
If M^2+ is 10, the neutral metal M must be 12. What has an atomic number of 12?