Scientists have established that some of the layers of Earth are solid, some are liquid, and some are semi-fluid. Explain how the scientists are able to determine the liquid and solid layers. Use at least two pieces of evidence to support your answer.

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided