Which of the following solutions have `pH lt 7`.

Options

A. `BaI_(2)`
B. `AI(NO_(3))_(3)`
C. `CH_(3)COONH_(4)`
D. `CsI`

Answer

B

Explanation

Salt of `W_(B)//S_(A)` have `pH lt 7`.
(Salt of `W_(A)//W_(B)` have `pH lt 7`, if acidic part is stronger, i.e., if `K_(a) gt K_(b)` or `pK_(b) gt pK_(a))`
a. Salt of `Ba(OH)_(2)(S_(B)) HI (S_(A))`
`:. pH = 7`
b. Salt of `A1(OH)_(3) (S_(B))` and `HNO_(3)(S_(A))`
` :. pH lt 7`.
c. Salt of `CH_(3)COOH (W_(A))` and `NH_(4)OH(W_(B))` (but `K_(a) = K_(b)`, so `pH = 7`.
d. Salt of `Cs(OH)(S_(B))` and `HI (S_(A))` so `pH = 7`.