Balance all of the following equations i.) Fe + H2O => Fe2O3 + H2
ii.) PbS + O3 => PbSO4 + O2
iii.) KNO3 => KNO2 + O2
iv.) Al + H2O => Al2O3 + H2

Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a differential and enrichment culture.