Final answer:
The pH scale is a measure of the acidity or basicity of a solution. A lower pH indicates a more acidic solution, while a higher pH indicates a more basic solution. In order to determine the order of decreasing pH for the given salts, we need to consider the ions produced when these salts dissolve in water.
Step-by-step explanation:
The pH scale is a measure of the acidity or basicity of a solution. A lower pH indicates a more acidic solution, while a higher pH indicates a more basic solution. In order to determine the order of decreasing pH for the given salts, we need to consider the ions produced when these salts dissolve in water.
a) KNO3: KNO3 dissociates into K+ and NO3- ions. This salt does not produce any ions that can affect pH, so it is a neutral salt.
NaF: NaF dissociates into Na+ and F- ions. F- ions react with water to form HF and OH- ions. Therefore, NaF solution is slightly basic.
NH4Cl: NH4Cl dissociates into NH4+ and Cl- ions. NH4+ reacts with water to form NH3 and H3O+ ions. Therefore, NH4Cl solution is slightly acidic.
From this information, the correct order of decreasing pH is (c) NH4Cl, KNO3, NaF.