Which choice represents a pair of resonance structures? view available hint(s) which choice represents a pair of resonance structures? a. n⋅⋅≡c−s−h and n⋅⋅≡c−s: − : b. o⋅⋅=n⋅⋅−f: and : n⋅=o⋅⋅⋅−f: c. h−h and : i−i: d. o−s⋅⋅⋅=o⋅⋅: and : o⋅⋅=s⋅⋅⋅−o:

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.