Which of the following salts on being dissolved in water gives `pH gt 7` at `25^(@)C`?

Options

A. KCN
B. `KNO_(3)`
C. `NH_(4)CI`
D. `NH_(4)CN`

Answer

A

Explanation

KCN hydrolysis to give KOH and HCN in water. KOH being a strong base easily neutralizes the weak acid HCN and the resulting solution becomes basic or `pH gt 7`
`KNO_(3)(aq) If KOH(SB) + HNO_(3)(SA)`, thus neutral
`NH_(4)CI(aq) If NH_(4)OH(WB) + HCI (SA)`, thus acidic `(pH lt 7)`
`NH_(4)CN(aq) If NH_(4)OH(WB) + HCN(WA),` thus neutral.
SA = strong acid , SB = strong base
WA = weak acid , WB = weak base.