The colloidal solution of $Fe(OH)_3$ in water is a .......

Which one of the following is used in the hardening of leather?

The ability of an ion to bring about coagulation of a given colloid depends upon

Given below are two statements:
Statement $I:$ In the coagulation of a negative sol,the flocculating power of the three given ions is in the order - $Al^{3+} > Ba^{2+} > Na^{+}$
Statement $II:$ In the coagulation of a positive sol,the flocculating power of the three given salts is in the order - $NaCl > Na_{2}SO_{4} > Na_{3}PO_{4}$
In the light of the above statements,choose the most appropriate answer from the options given below:

Electrophoresis is used

Gold sol is not: