Which event occurred approximately 4.6 billion years ago

Which statements are accurate about snow flakes

[ou.01]which of these is the most likely use of an electromagnetic wave which has wavelength shorter than microwaves but longer than visible light? o heat food safely o neat food safely o take images of bones and teeth o transmit radio and cellular phone signals o take images of bones and teeth o transmit radio and cellular phone signals o detect the location of objects which emit heat

The layers of earth are based on what two sets of characteristics?