The charges on the colloidal \( \mathrm{CdS} \) sol and \( \mathrm{TiO}_{2} \) sol are, respectively [JEE Main 2021, 18 …

A colloid is a combination in which one ingredient is suspended throughout another substance and is made up of minutely scattered insoluble particles.
Colloidal solutions are divided into positively charged and negatively charged colloids depending on the type of charge on the particles of the dispersed phase.
Examples of negatively charged colloids are Metal sulfides, Metal dispersions, Sulfur solution, etc.
Examples of Positively charged colloids are Metal hydroxides, Metal oxides, basic dyes, etc. Cadmium sulfide is a yellow color sulfide of Cadmium metal so, it is a negatively charged colloidal solution.
Titanium oxide is a white color, oxide of Titanium metal so, it is a positively charged colloidal solution.