Answer
See explanation below.
Work Step by Step
2 Cu+ (aq) + PbO2(s) + 4 H+(aq) + SO4 2-(aq) --> 2 Cu2+(aq) + PbSO4(s) + 2 H2O(l)
E cell = E°PbO2- E°Cu2+
= 1.70 V - (0.15 V)
= 1.55 V
Reaction is spontaneous E cell is positive.
Second part.
H2O2(aq) + Ni2+(aq)--> 2 H+(aq) + O2(g) + Ni(s)
Ecell = E°Ni2+ - E°O2
= -0.25 V - (0.68 V)
= -0.93 V
Reaction is non spontaneous as E cell is negative.
