An electrochemical cell was constructed based on this oxidation-reduction reaction
Sn + 2 Ag+ + Sn2+ + 2 Ag
Which metal is the anode?

Awhite powder is added to a solution. the images show observations made before the powder is added, just after the powder has been added, and a little while later. (the liquid in the small beaker is phenol red solution.) what evidence shows that a chemical change has taken place?