Helium has an atomic number of 2, so it's outer energy level is full. helium is considered a)neutral
b)inert
c)an anion
d)a cation

In the practice of science, this type of reasoning is used to develop explanations.

Pentane with molecular formula c5h12, exists in three isomeric forms. one shows linear carbon chains, another has one -ch3 groups present on the third carbon atom, and the third has two -ch3 groups present on the second carbon atom. what types of isomers are these? a. geometric isomers b. structural isomers c. halotropic isomers

Which of the following would involve looking at different structures of organisms and comparing how similar they are? a. vestigial structuresb. radiometric datingc. homologous structures