EoMg2+/Mg = -2.37 V
EoZn2+/Zn = -0.76 V
Which reaction is spontaneous?
(a) MgSO4 + Zn → ZnSO4 + Mg
(b) ZnSO4 + Mg → MgSO4 + Zn
Answer & explanation
Correct answer: option 2
EoMg2+/Mg < EoZn2+/Zn
So Mg lie above in electrochemical series. Mg can displace metal from zinc's salt solution which lies below it.
ZnSO4 + Mg → MgSO4 + Zn is spontaneous reaction.