A. A piece of Iron being heated until it melts
Because it goes from solid to liquid.
A physical change is changing from solid to a liquid, a liquid to a gas, a gas to a liquid, a liquid to a solid, a solid to a gas, or a gas to a solid.
Just add up all the "exponents" and you'll get 25 which is Manganese or Mn on the periodic table!
It represents a conservation in mass because the actual mass of water isn’t changing. The relationship between the molecules and the density of the water is. There is still the same amount of mass.