Which describes the fourth state of matter known as plasma

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

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)

Apump contains 0.5 l of air at 203 kpa. you draw back on the piston of the pump, expanding the volume until the pressure reads 50.8 kpa. what is the new volume of the air pump