What is "free" nitrogen?
A) nitrogen that is ready for plants to use
B) nitrogen that has been fixed by bacteria
C) nitrogen that cannot be used by organisms
D) nitrogen that is returned to the soil by decomposes

What is the independent variable in this investigation? mass volume sample number substance density

Sodium sulfate dissolves as follows: na2so4(s) → 2na+(aq) + so42- (aq). how many moles of na2so4 are required to make 1.0 l of solution in which the na concentration is 0.10 m?

•what conclusions can you make about the relationship between the volume of a gas and its temperature? • what conclusions can you make about the relationship between the volume of a gas and its pressure? • what possible variables have you not accounted for? as you did the procedures, is it possible that the atmospheric pressure may have changed? if it did change over the course of your experiment, then how would your results have been affected?