B and c
Its because heavier objects have a higher gravitational force
A heterogeneous mixture composes of non- uniform components, so the concrete would be the answer, because you can tell the components from one another.
The best example of hypothesis which leads to new experiment methods was done by Morgan where he used fruit flies.
Thomas Hunt Morgan continues on genetic research which is of Gregor Mendel.
Between a cation, which is usually a metal, and an anion, which is usually a nonmetal. A covalent bond involves a pair of electrons being shared between atoms.