Why is the r. a.m. value used? a. a single atom cannot be isolated, so only the average size of a group of atoms can be measured. b. the r. a.m. value is used to determine how many isotopes an element has. c. atoms are too small for their masses to be measured directly. d. none of these

What method(s) do plants use to obtain nitrogen? select all that apply. absorb it from the atmosphere use bacteria to convert nitrogen to usable form obtain usable nitrogen compounds from the soil absorb nitrogen from water taken in at the roots

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

What are the first three quantum numbers for the electrons located in subshell 2s?