Is H2O made up of three Elements?

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?

What is the importance of interlocking the fingers and rubbing while washing hands? the palms are the dirtiest parts of the hands. the spaces between the fingers get washed. the backs of the hands get washed. the fingernails are the dirtiest parts of the hands

Which of the following are in a chemical family a. ca, sc, k b. cu, ag, au c. so, ge, sb