1. Rubidium has 2 isotopes in nature, and the average atomic mass is 85.557 amu. Rb-85 has a relative abundance of 72.15%.
What is the relative abundance of the other isotope, Rb-87?

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.