Which of the following preparations are condensation methods?

AOxidation of $H X_{2} S$ with $SO X_{2}$ to give a sulphur sol: $2 H X_{2} S + SO X_{2} 3 S + 2 H X_{2} O$
BGrinding a coarse suspension of a solid in a colloid mill to give a sol
CHydrolysis of $FeCl X_{3}$ in boiling water to give an $Fe (OH) X_{3}$ sol
DPeptization of freshly precipitated $Fe (OH) X_{3}$ with a little $FeCl X_{3}$ solution

Answer: A, C

Condensation methods build colloidal particles from atoms or molecules, as in the oxidation of

H X_{2} S

to sulphur and the hydrolysis of

FeCl X_{3}

. Grinding in a colloid mill and peptization break up a coarse solid or a precipitate into colloidal size, so they are dispersion methods.