Which of the following reactions will occur spontaneously as written?
Sn^4+ (aq) + Fe^2+ (aq) = Sn^2+ (aq) + Fe(s)
3Fe^2+ (aq) + Cr^3+ (aq) = Cr(s) + 3Fe^3+ (aq)
2Cr^3+ (aq) + 3Sn^2+ (aq) = 3Sn^4+ + 2Cr(s)
Sn^2+ (aq) + Fe^2+ (aq) = Sn^4+ (aq) + Fe^3+ (aq)
2Cr(s) + 3Fe^2+ (aq) = 3Fe(s) + 2Cr^3+ (aq)