It's pretty easy, please help, I'm confused on it.

What volume of a 0.25 m solution can be made using 0.55 moles of ca(oh)2

Before the can be observed by using a transmission electron microscope, cells are sliced into very thin sections. what disadvantage does this procedure present in the study of cellular parts

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?