Which has the highest `pH`?

Options

A. `CH_(3)CO^(-)OK^(+)`
B. `Na_(2)CO_(3)`
C. `NH_(4)Cl`
D. `NaNO_(3)`

Answer

B

Explanation

`pH=log.(1)/([H^(+)])`
pH is inversely proportional to hydrogen ion concentration. As concentration of `H^(+)` decreases pH increases and vice-versa.
Ammonium chloride `(NH_(4)Cl)` is a salt of weak base and strong acid. So, its aqueous solution will be acidic as
`NH_(4)Cl + H_(2)O rarr underset("Weak base")(NH_(4)OH)+underset("Strong acid")(HNO_(3))`
So, pH of `NaNO_(3)` is 7.
Potassium acetae `(CH_(3)COOK)` is salt of strong base and weak acid. Its aqueous solution will be basic and pH value will be greater than 7.
Sodium nitrate `(NaNO_(3))` is the salt of strong acid and strong and strong base. So, its aqueous solution is neutral as
`NaNO_(3)+H_(2)O rarr underset("Strong base")(NaOH)+underset("Strong acid")(HNO_(3))`
So, pH of `NaNO_(3)` is 7.
Potassium acetate `(CH_(3)COOK)` is salt of strong base and weak acid. Its aqueous solution will be basic and pH value will be greater than `7 ~~8.8`
`CH_(3)COO^(-)K^(+)+H_(2)O rarr underset("Weak acid")(CH_(3)COOH)+ underset("Strong base")(KOH)`
Sodium carbonate `(Na_(2)CO_(3))` is a salt of strong base and weak acid. Its aqueous solution is also basic and its pH value will be more than 10.
i.e. highest among them.
`Na_(2)CO_(3)+H_(2)O rarr underset("Strong base")(2NaOH)+ underset("Weak acid")(H_(2)CO_(3))`