The term "ALUM" refers to a class of compounds of general formula QZ(SO4)2•12H2O where Q and Z are two different metals. A 25.00 g sample of a certain alum is heated to drive off the crystal water; the anhydrous residue weighs 14.264 g. Treatment of the residue with excess NaOH precipitates all the Z as Z(OH)3 which weighs 5.355 g. Identify the two metals.
A. K and Al B. Na and Al C. K and Cr D. K and Fe