Your teacher gives you a sample of an unknown element which is sealed in a glass tube at room temperature. At the bottom of the tube there is a small amount, a few drops at the most, of a red-black filmy liquid, and above it is a red vapor. What is this element likely to be

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.