Assuming `100%` ionization in case of strong electrolytes which of the following will have minimum pH

Options

A. 0.1 M `NH_(4)Cl`
B. 0.1 M `(NH_4)_(2)SO_(4)`
C. 0.1M `(NH_(4))_(3)PO_(4)`
D. All will have same pH.

Answer

B

Explanation

Minimum pH means maximum `[H^(+)]`
`NH_(4)Cl rarr NH_(4)^(+) +Cl^(-)`
`NH_(4)^(+) +H_(2)O hArr NH_(4)OH +H^(+)`
`:. [H^(+)] =0.01 xx K_(h)`
In case of `(NH_(4))_(2)SO_(4)`
`[H^(+)]=0.02 xx K_(h)`
However `(NH_(4))_(3)PO_(4)` will be almost neutral `(pH ~~7)` as it is a salt of a weak acid and a weak base. Thus pH will be minimum (i.e., highest `H^(+)` conc. ) in case of 0.01 M `(NH_(4))_(2)SO_(4)`