MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

For a cell reaction to be spontaneous under standard conditions, the standard cell potential E^ _ cell must be positive. E^ _ cell = E^ _ cathode - E^ _ anode Evaluating the given options: For Ca(s) + Cd ^ 2+ (aq) Ca ^ 2+ (aq) + Cd(s) : Cathode (reduction): Cd ^ 2+ Cd Anode (oxidation): Ca Ca ^ 2+ E^ _ cell = -0.403 - (-2.866) = +2.463 V (Spontaneous) For 2 Br ^- (s) + Sn ^ 2+ (aq) Br _2 (l) + Sn(s) : Cathode: Sn ^ 2+ Sn Anode: 2 Br ^- Br _2 E^ _ cell = -0.136 - 1.08 = -1.216 V (Non-spontaneous) For 2 Ag(s) + Ni ^ 2+ (aq) 2 Ag ^+ (aq) + Ni(s) : Cathode: Ni ^ 2+ Ni Anode: Ag Ag ^+ E^ _ cell = -0.257 - 0.799 = -1.056 V (Non-spontaneous) For 2 Au(s) + Zn ^ 2+ (aq) 2 Au ^+ (aq) + Zn(s) : Cathode: Zn ^ 2+ Zn Anode: Au Au ^+ E^ _ cell = -0.763 - 1.68 = -2.443 V (Non-spontaneous) The only reaction with a positive standard cell potential is the first one. Answer: Ca(s) + Cd ^ 2+ (aq) Ca ^ 2+ (aq) + Cd(s) , [E^0_ Ca = -2.866 V & E^0_ Cd = -0.403 V]