The most important property of lyophobic colloidal dispersion is that the colloidal particles always carry an electric change. The nature of this charge is the same on all the particles in a given colloidal solution and may be either positive or negative. Which of the following is an electronegative colloid?

Options

A. Arsenious sulphide sol
B. Ferric hydroxide sol
C. Haemoglobin
D. Methylene blue

Answer

A

Explanation

The dispersion medium has an equal and opposite charge making the system neutral as a whole. Due to similar nature of the charge carried by the particles, they repel each other and do not combine to form bigger particles. That is why a lyophobic sol is stable and particles do not settle down. Metallic hydroxides (or hydrated metallic oxides), some metals (such as `Bi,Pb,Fe)`, basic dyes (such as methyl violet and methylene blue) are electropositive colloids while metallic sulphides (such as `As_(2)S_(3)S,b_(2)S_(3),CdS`), many metals (such as `Cu,Ag,Au,Pt`), acidic dyes (eosin, congo red) are electronegative colloids.