Since all of these elements are under the same conditions, volume only varies based on the number of atoms present. You can find the number of atoms in a given sample by dividing the weight of the sample by the molar mass.
Aluminum has a molar mass of 26.9 so 10/26.9 = .371 moles
go on to get Ti= 10 / 47.88 =.209 moles
Mg = 10.0 / 24.3 = 0.412 moles
Zn = 10 / 65.37 = .153 moles
Since there are less moles of Zn, it has the smaller volume at STP than the other elements.
