' X ' is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of gold sol to which 1 mL of 10 % NaCl is added. What is the gold number of ' X '?

Step-by-step solution

Gold number is the number of milligrams of the protective colloid which prevent the coagulation. When 1 ml of 10 % solution of sodium chloride is added then coagulation happens X is the protecting colloid. Smaller the gold number of protecting colloid. Greater is the protecting power. So the gold number of X is 25 .