Plate tectonics are the broken plates of earth that move around and form the different plate boundaries
After 3 half life periods you would have 5 grams of krypton left because half of 40 is 20 half of 20 is 10 and half of 10 is 5
Heat moves in three ways:Radiation, conduction, and convection. Radiation happens when heat moves as energy waves, call infrared waves,directly from its source to something else.This is how the heat from the Sun gets to Earth.In fact,all hot things radiate heat to cooler things:).hope this helps