I went on an airplane and brought along a bag of chips. When I was in mid-air, the bag looked completely stretched out and about to burst. What could be the cause of this expansion?

a:

by the combination of an unlimited number of elements

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.