Explain why pure water is a compound, but water from a fountain is not.

Which compound contain an iron with a 3+ charge

What are the first two quantum numbers for the electrons located in subshell 4d? what are the first three quantum numbers for the electrons located in subshell 2s? how many electrons can be held in a sublevel l = 3? how many electrons can be held in the energy level n = 4? how many electrons in an atom can share the quantum numbers n = 4 and l = 3?

Which electron configuration represents the electrons in an atom of sodium in the ground state at stp