What mass of copper would be liberated
by the same quantity of electricity which liberated 11.20dm³ of hydrogen measured at s. t.p
(Cu= 64, H= 1, GM V = 22.4 dm³)

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.

Solubility would be your answer.