Answer:
Salt is the variables being tested.
Explanation:
Solubility of salts are the variables being tested in the experiment by changing temperature. Variables are those factors or elements whose values are changing. Salts are put in the two test tube which has the same temperature i. e. 25°C. Then the temperature of the test tube will be increases and due to increase in temperature, the solubility of salts in water increases and the whole solution will be uniform while salts remain at the bottom due to no increase in temperature.
