Question

Which salt has a pH < 7?

KBr
HCOOK
CaSO4
NH4NO3

Answer 1

The answer is NH4 NO3

Answer 2

`NH_(4)NO_(3)` has pH<7

Step-by-step explanation:

pH of salt depends on species generated through hydrolysis of the given salt.

Hydrolysis equilibrium of
`NH_(4)NO_(3)` is given below:

`NH_(4)NO_(3)+H_(2)O\rightarrow NH_(4)OH+HNO_(3)`

`NH_(4)OH` is a weak base and
`HNO_(3)` is a strong acid. So species obtained through hydrolysis of
`NH_(4)NO_(3)` is a mixture of strong acid and weak base.

Hence the the salt solution will be acidic in nature. That means pH of solution is less than 7.