Which colorless and odorless gas, produced by radioactive decay of uranium-238, is considered to be a form of pollution?
a. boron
b. oxygen
c. radon
d. hydrogen

Endeleev saw trends in the physical and chemical properties of elements when he organized them by

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 of c6h18o3? ch3o c2h5o c2h6o c2h5o5