What causes the changes in air pressure on the earth surface

Once similarity and one difference between a mixture of elements and a mixture of compounds

Substance a is a nonpolar liquid and has only dispersion forces among its constituent particles. substance b is also a nonpolar liquid and has about the same magnitude of dispersion forces among its constituent particles. when substance a and b are combined, they spontaneously mix.

In which phase of mitosis do the spindle fibers pull the chromosomes apart to opposite sides of the cell ?