3. Write the equilibrium expressions for Key for the following reactions. a. 203 (8) = 3 02 (8)
b. 2 C2H4 (g) + 2 H2O(g) = 2 C2H6 (g) + O2 (g)
c. 2 H2(g) + S2(g) + 2 H2S (8)
d. 4 NH3(g) + 5 O2 (g) = 4 NO (8) + 6 H20 (8)

The answer for #3 is c but i don't 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

Precision can be defined as the o exact center of a data set. o reproducibility of a measured value. o correlation between two variables that are measured in a data set agreement between a measured value and an accepted value.