please help. Describe the procedure for calculating the percent composition of an element in a compound, according to mass.

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

If a polyatomic ionic compound has gained two hydrogen ions, then how does its name begin?

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5