14) a) Elements: i, ii, iv, vi
b) Compounds: iii, v
15) A chemical formula tells us the elements present in a substance and the number of atoms in that substance.
16) a) 3 Hydrogen atoms, 1 Phosphorus atom and 4 Oxygen atoms
b) 1 Sodium atom, 1 Oxygen atoms and 1 Hydrogen atom.
c) 1 Sulfur atom and 2 Oxygen atoms
17) a)
c) one gaseous H2 (hydrogen) molecule plus one gaseous Cl2 (chlorine) molecule yields two gaseous HCL (hydrochloric acid) molecules
c2) two aqueous H202 (hydrogen peroxide) molecules yields two H20 (water) molecules plus one gaseous 02 (oxygen) molecule
18) a) NaHCO3 + HCl --> NaCl + H2O + CO2
b) C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O
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