Answer: \(NH_4NO_3\)
Explanation: Acidic salts are those which are formed by combination of strong acid and a weak base and have acidic pH of less than 7.
Basic salts are those which are formed by combination of weak acid and a strong base and have basic pH of more than 7.
Neutral salts are those which are formed by combination of weak acid and a weak base or by combination of strong acid and a strong base and have neutral pH equal to 7.
1) \(KBr\) is a neutral salt formed by combination of strong acid \(HBr\) and a strong base \(KOH\).
2) \(HCOOK\) is a basic salt formed by combination of weak acid \(HCOOH\) and a strong base \(KOH\).
3) \(CaSO_4\) is a neutral salt formed by combination of strong acid \(H_2SO_4\) and a strong base \(Ca(OH)_2\).
4) \(NH_4NO_3\) is an acidic salt formed by combination of strong acid \(HNO_3\) and a weak base \(NH_4OH\).
