Acopper sheet is heated in a furnace until it melts. the hot liquid copper is then cooled until it becomes solid again. compare the mass of the copper before and after melting. a) the new solid copper is lighter than the original sheet. eliminate b) the new solid copper is heavier than the original sheet. c) the new solid copper is the same weight as the original sheet. d) the molten copper was lighter than the sheet or the new solid.