Water is used in a hot water bag because – (1) It is easily available (2) It has high specific gravity (3) It has high specific heat (4) It is a liquid substance
(3) It has high specific heat Explanation: Water has the highest specific heat of any known substance except hydrogen; that is, it requires more heat to raise the temperature of water a definite number of degrees than it does to raise the temperature of an equal amount of any other substance the same number of degrees.