Question

The `pK_(b)` of `CN^(Theta)` is `4.7`. The `pH` is solution prepared by mixing `2.5 mol` of `2.5 mol` of `KCN` of `2.5 mol` of `HCN` in water and making the total volume upto `500mL` is
A. `10.3`
B. `9.3`
C. `8.3`
D. `4.7`

Answer 1

Correct Answer - B
It forms basic buffer
`pOH = pK_(b) + log ((2.5//500)/(2.5//500)) = 4.7`
`pH = 14 - 4.7 = 9.3`.