What is the formula to find the area of circle

What neutral atom is isoelectronic to mn+4

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

One way that radioactive waste is treated is by burying it in repositories. the repositories are found only in states with very low populations. true or false? a. trueb. false(also i meant to put high school but it put down middle school instead)