6. Which of the following statements is/are TRUE of metals and non-metals? l. Non-metals are heat conductors.
ll. Aluminum, copper and iron are non-metals.
III. Phosphorus and sulfur are poor conductors of heat and electricity
IV. Metals have luster.

A. I only
B. III only
C. III and IV
D. I and II

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.