Question

Find the positively charged sol from the following

• A. Ag
• B. $\mathrm{Al}(\mathrm{OH}{)}_3$
  
• C. Methylene blue
• D. Congo red

Answer 1

Answer: (B), (C)

The correct options are
B $\mathrm{Al}(\mathrm{OH}{)}_3$

C Methylene blue

Positively charged sols:
Hydrated metallic oxides like $A{l}_2{O}_3.x{H}_{2}O,Cr{O}_3.x{H}_{2}OandF{e}_2{O}_3.x{H}_{2}O$, etc. Basic dyes like methylene blue sol. Haemoglobin (blood) , oxides like $Ti{O}_2$ sol.
Negatively charged sols:
Metals sols like copper, silver,gold sols. Metallic sulphides like $A{s}_2{S}_3,S{b}_2{S}_3,CdS$ sols. Acid dyes like eosin, congo red sols. Sols of starch, gum, gelatin,clay, charcoal, etc.