How many moles of water are produced from the reaction of oxygen with four moles of propane (C3H8)? C3H8 + 5O2 --> 3CO2 + 4H2O

Iknow #2 is d. i just need to know why

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

What is the empirical formula for c4h8o2