Which is a substance that is made up of only one type of atom

Much of the general structure and physical properties of the interior of the earth are inferred from: a)deep oil and gas bore holes b)geologic investigations c)analysis of seismic waves d) study of volcanoes

Which compounds have the empirical formula ch2o? a.c2h4o2 b.c3h6o3 c.ch2o2 d.c5h10o5 e.c6h12o6

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?