`pOH=7-0.5pK_a+0.5 pK_b` is true for aqueous solution containing which pair of cation and anion :

The pK_(a) of a weak acid (HA) is 4.5 . The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is:

The pK_(a0 of a weak acid (HA) is 4.5. The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is :

The pK_a of a weak acid (HA) is 4.5 The pOH of an aqueous buffered solution of HA in which 50% of it is ionised is

The pH of 0.01M HCN solution for which pK_(a) is 4 is