In which case `pH` will not change on dilution

Options

A. `0.01 M CH_(3)COONa+0.01 M CH_(3)COOH` buffer
B. `0.01 M CH_(3)COONH_(4)`
C. `0.01 M NaH_(2)PO_(4)`
D. in all cases

Answer

D

Explanation

Mixture of sodium acetate and acetic acid is a buffer of `pH` value equal to `pK_(a)` so its buffer capacity is very high and hence its `pH` will not change signficantly while `CH_(3)COONH_(4)` is a salt of weak acid `CH_(3)COOH` and weak base `NH_(4)OH` whose magnitude of `K_(a)` and `K_(b)` are equal. So its `pH` does not depend upon concentration. Furthermore, `NaH_(2)PO_(4)` is , in fact, a single solute buffer