A button cell used in watches function as following.
Zn_(s) + Ag₂O_(s) + H₂O_(l) $$\rightleftharpoons$$ 2Ag_(s) + Zn²⁺_(aq) + 2OH^$$-$$_(aq)

If half cell potentials are
Zn²⁺_(aq) + 2e^$$-$$ $$ \to $$ Zn_(s);  E^o = $$-$$0.76 V
Ag₂O_(s) + H₂O_(l) + 2e^$$-$$ $$ \to $$ 2Ag_(s) + 2OH^$$-$$_(aq), E^o = 0.34 V

The cell potential will be

At 25^oC molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm^$$-$$1 cm² mol^$$-$$1 and at infinite dilution its molar conductance is 238 ohm^$$-$$1 cm² mol^$$-$$1. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be

Standard reduction potentials of the half reactions are given below :
F_2(g) + 2e^$$-$$ $$ \to $$ 2F^$$-$$_(aq) ;   E^o = + 2.85 V
Cl_2(g) + 2e^$$-$$ $$ \to $$ 2Cl^$$-$$_(aq) ;   E^o = + 1.36 V
Br_2(l) + 2e^$$-$$ $$ \to $$ 2Br^$$-$$_(aq) ;   E^o = + 1.06 V
I_2(s) + 2e^$$-$$ $$ \to $$ 2I^$$-$$_(aq) ;  E^o = + 0.53 V

The strongest oxidising and reducing agents 23 respectively are