Which of the following sols are correctly matched with their corresponding charges?

(A) \(Cr(OH)_3\) sol: negatively charged sol

(B) \(TiO_2\) sol: positively charged sol

(C) \(CdS\) sol: positively charged sol

(D) Gum: negatively charged sol

(E) Silver sol: positively charged sol

Choose the correct answer from the options given below:

(B) and (D) only

The correct answer is option 4. (B) and (D) only.

\(TiO_2\) sol is positively charged because titanium dioxide (\(TiO_2\)) typically forms positively charged ions (\(Ti^{4+}\)) when dispersed in a solvent. These positively charged ions stabilize the sol, resulting in a positively charged colloidal solution.

Gum, such as gum arabic, is negatively charged due to the presence of functional groups like carboxylate (\(-COO^-\)) or hydroxyl (\(-OH\)) groups. These groups can ionize in water, releasing negatively charged ions, which impart a negative charge to the colloidal particles.

Therefore, options (B) and (D) are correct because both \(TiO_2\) sol and gum sol are matched correctly with their corresponding charges: positively charged and negatively charged, respectively.