Here Cu (II) reduced to Cu (0). Al would be strong reducing agent to do so. Now ... Compare Al and Cu reduction potentials. Al3+(aq) + 3 e– ----> Al(s) -1.66 Cu(OH)2(s) + 2 e– ----> Cu(s) + 2 OH–(aq) -0.36. It implies that reduction potential of Cu is more than Al hence this reaction is not feasible bcuz copper is a reducing agent ( oxidize itself or reduces others). But still you can balance...practically this reaction seems impossible bcuz of above reason.
