The periodic table . is arranged by atomic mass
was developed by early alchemists
is arranged by number of protons
is divided into vertical periods and horizontal groups

Four types of motile cells in human body?

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

What element does susan b. anthony include in this passage to strengthen her argument?