would you suspect the density of the mantle to be greater or less than the crust? why?

The density of the mantle is more than that of the crust.

Earth is the only planet in the solar system which habitats life in it. It is made up of three layers namely outer layer called crust, middle layer called mantle and the innermost layer called core. The outer layer crust is the region of the earth where lives exist.  

When we compare the density of the three layers with one another it is understood that density of the mantle to be greater than the crust. The density of top as well as bottom region of crust comprising is 5.1 , whereas in case of mantle it is 7.8 .

Thus, it is proved that mantle is heavier than the crust.

the sphincter muscles at the end of the digestive tract is the anus.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.