The outer core of the earth is made mostly of question 4 options: solid iron and nickel water unknown materials molten iron and nickel

How do the energy differences between the higher energy levels of an atom compare with the energy difference between the lower energy level of the atom

What does x represent in the formula for the compound xcl4?

Transportation is the largest single source of air pollution in the united states. air pollution can harm the environment and human health. which technology could offer a solution to this problem? mufflers that reduce noise motors that run on electricity tires that improve gas mileage