For an atom’s electrons, how many energy sublevels are present in the principal energy level n = 4?

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

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

Find the number of grams of hcl needed to react completely with .50 moles of magnesium.