Why is the average atomic mass used when calculating grams of a substance? A. The number of isotopes in the sample is constantly changing. B. The average atomic mass is known to more significant figures, O C. The elements in the substance are mixtures of their isotopes. D. The exact weights of the isotopes are not known.​

8) warming your hands by a fire is an example if which heat transfer? a. conduction b. convection c. radiation d. none of these

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.

He nucleus contains the cells genetic material in the form of dna. dna is organized into our chromosomes, which are made up of thousands of that determine our traits.