If a substance has a half-life of 150 million years, what fraction of the atoms remain after 300 million years?
A. 1/8
B. 1/2
C. 1/4
D. 1/16

right

explanation:

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.