Why does mantle rock begin to sink back towards the lower mantle from the area closest to the crust? (Science/Plate Tectonic Movement)

Explain why pure hydrogen cyanide does not conduct electricity, but become a conductor when it is dissolved in water? (at room temp, pure hcn exists as a volatile liquid)

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)

What is the percentage of hydrogen in nitrogen trihydride