MHT CET202613 April 2026Morning ShiftChemistryElectrochemistryActual
Identify from following cell reactions that is spontaneous under standard state of conditions.
Options
- ACa(s) + Cd ²⁺ (aq) Ca ²⁺ (aq) + Cd(s) , [E^0_ Ca = -2.866 V & E^0_ Cd = -0.403 V ]
- B2 Br ^- (s) + Sn ²⁺ (aq) Br ₂ (l) + Sn(s) , [E^0_ Br = 1.08 V & E^0_ Sn = -0.136 V ]
- C2 Ag(s) + Ni ²⁺ (aq) 2 Ag ^+ (aq) + Ni(s) , [E^0_ Ag = 0.799 V & E^0_ Ni = -0.257 V ]
- D2 Au(s) + Zn ²⁺ (aq) 2 Au ^+ (aq) + Zn(s) , [E^0_ Au = 1.68 V & E^0_ Zn = -0.763 V ]
Correct answer
A. Ca(s) + Cd ²⁺ (aq) Ca ²⁺ (aq) + Cd(s) , [E^0_ Ca = -2.866 V & E^0_ Cd = -0.403 V ]
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 ^+