Which of the following are considered pure substance? ?
a. element
b. compound
c. homogenous mixture
d. heterogeneous mixture

__can be defined as which velocity changes

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.

Animals that reproduce sexually either do it through external or internal fertilization. read the following statement and decide if it is true or false. birds reproduce through external reproduction which is because the female will then be able to protect the egg.