Silicon dioxide (SiO2) and aluminum oxide (Al2O3) are the two most abundant compounds in the . A.
universe
B.
Earth's oceans
C.
Earth's atmosphere
D.
Earth's crust

Eath's crust

Explanation:

Silicon dioxide (SiO2) and aluminum oxide (Al2O3) are the two most abundant compounds in the Earth's crust. This explains why oxygen, silicon, and aluminum are the three most abundant elements in the crust.

The most abundant compound in the universe is water.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex