Students are given the following data for determining the average atomic mass of Lithium: A sample of Lithium consists of 400 atoms:

30 atoms are the isotope Lithium-6 (6.015 amu)

370 atoms are the isotope Lithium-7 (7.016 amu).

Which student correctly calculated the correct average atomic mass of Lithium and why?

Which of these is an intensive property of a substance

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt

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.