How many of the following may cause coagulation in colloidal solutions?
(a) Tanning
(b) Dialysis
(c) Cataphoresis
(d) Mixing of a lyophilic sol with a lyophobic sol
(e) Mixing of two lyophobic sols
(f) Mixing sol-I $({\mathrm{AgNO}}_3$ with excess KI) and sol-II (KI with excess ${\mathrm{AgNO}}_3$ )
(g) Addition of alcohol to a hydrophilic sol followed by addition of small quantity of electrolyte
(h) Centrifuging
(i) Freezing
 

Coagulation is the process in which aggregation or accumulation of colloidal particles are settle down as a precipitates.

Tanning, Dialysis, Cataphoresis, Centrifuging and Freezing are cause coagulation in colloidal soution.

Also, mixing of a lyophilic sol with a lyophobic sol, two lyophobic sols, sol-I $({\mathrm{AgNO}}_3$ with excess KI) and sol-II (KI with excess ${\mathrm{AgNO}}_3$ ) and addition of alcohol to a hydrophilic sol followed by addition of small quantity of electrolyte are cause coagulation.