Plz answer very fast anyone knows

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?

Describe the forces both attractive and repulsive that occur as two atoms move closer together.

The size (radius) of an oxygen molecule is about 2.0 ×10−10m. make a rough estimate of the pressure at which the finite volume of the molecules should cause noticeable deviations from ideal-gas behavior at ordinary temperatures (t= 300k ). assume that deviatons would be noticeable when volume of the gas per molecule equals the volume of the molecule itself.