Answer:
Warm salt water is a natural disinfectant that is used against sore throat and swollen gums. Warm salt water kills some bacteria present in sore throat and swollen gums because due to the high concentration of salt some bacteria lose water from their cell which results in the killing of bacteria.
Therefore warm salt water can relieve pain of swollen gums and reduce the number of bacteria present in the sore throat and swollen gums because of its disinfectant property.
Because of this property of salt, it is used in high amounts in some food items to preserve food from bacteria.