Select the correct answer. Identify Bohr's model of the atom. His model describes the reactivity of an element based on its number of valence electrons.

Iknow #2 is d. i just need to know why

Which fact represents evidence for the big bang theory?

The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is made to illustrate which of the following? a. that atoms are indivisible b. that atoms are very small c. that atoms are very large d. that in a copper penny, there is one atom for every person on earth