Which of these statements is true?
(a)All spontaneous reactions have a negative enthalpy change
(b)All spontaneous reactions have a positive entropy change
(c)All spontaneous reactions have a positive free-energy change
(d)All spontaneous reactions have a negative free-energy change
(e)All spontaneous reactions have a negative entropy change

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.

answerambulatory;