Question

Which one is a spontaneous reaction?

Pd(s) + Be2+(aq) → Be(s) + Pd2+(aq)

3Sn(s) + 2Ga3+(aq) → 2Ga(s) + 3Sn2+(aq)

Be(s) + Sn2+(aq) → Sn(s) + Be2+(aq)

3Pd(s) +2Ga3+(aq) → 2Ga(s) + 3Pd2+(aq)