select correct statement (s) :
blood is a colloidal solution,
Alum is used in water purification,
River water is a colloidal solution of clay,
Colloidal medicines are more effective due to large surface area.
A
blood is a colloidal solution
B
Alum is used in water purifiaction
C
River water is a colloidal solution of clay
D
Colloidal medicines are more effective due to large surface area
