Tollen's reagent is used for the detection of aldehyde when a solution of `AgNO_(3)` is added to glucose with `NH_(4)OH` then gluconic acid is formed
`Ag^(+) + e^(-) rarr Ag , E_("red")^(@)= 0.8V`
`C_(6)H_(12)O_(6) + e^(-) rarr C_(6)H_(12) O_(7)` (Gluconic acid) `+2H^(+) + 2e^(-) , E_("red")^(@)= -0.05V`
`Ag(NH_(3))_(2)^(+) + e^(-) rarr Ag(s) + 2NH_(3) , E^(@)= -0.337V`
[Use `2.303 xx (RT)/(F)= 0.0592 and (F)/(RT)= 38.92` at 298K]
When ammonia is added to the solution, pH is raised to 11. Which half-cell reaction is affected by pH and by how much ?

Options

A. `E_("oxd")` will increase by a factor of 0.65 from `E_("oxd")^(@)`
B. `E_("oxd")` will decrease by a factor of 0.65 from `E_("oxd")^(@)`
C. `E_("red")` will increase by a factor of 0.65 from `E_("red")^(@)`
D. `E_("red")` will decrease by a factor of 0.65 from `E_("red")^(@)`

Answer

C

Explanation

On increasing the concetration of `NH_(3)`, the concentration of `H^(+)` ions decreases. Therefore, `E_("red")` increases.