12. By convention (agreement of the scientific community for consistency) magnetic field lines...

A. always start on the north pole and terminate (end) on the South Pole

B. start at infinity and point toward each pole

C. start at each pole and go outward

D. always start on the south pole and terminate (end) on the north pole.

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer. the ice dissolves oxygen from the air, forming a denser crystalline matrix. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds.