A carbide ion is an anion of carbon atom with two carbon atoms with a triple bond connected to each other. Since this carbide ion is a negatively charged ion, in order to convert carbide ion to its neutral carbon atom, it has to give up/remove four electrons.
Iron is the answer. Becaues its solid and it's particles are closest to each other. And well.metals are good at transferring heat.
In radio communication, "amplitude modulation" refers to encoding a wave with information by adjusting the height (amplitude) of the waves. <em>(a)</em>
Well, in some systems the atoms melt or burn or change state like from liquid to gases when they reach a certain temperature. This could decrease the energy in the system.
Hope I helped