How many moles of H2 are needed to react with 6.8 mol of O2? How many moles of H2O form when 4.3 mol of O2 reacts?
Fe2O3(s)+3H2(g)→2Fe(s)+3H2O(l) Calculate the mass of Fe.
Al2S3(s)+6H2O(l)→2Al(OH)3(aq)+3H2S( g) Calculate the mass of Al(OH)3.

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false