The most common polar and acidic support used in adsorption chromatography is silica. The surface silanol groups present on silica effectively adsorb polar compounds, making it particularly well-suited for basic substances. Alumina, being polar and basic, is also widely used as an adsorbent in adsorption chromatography. Together, these make the pair of adsorbents utilized frequently for such purposes.
Which compound is added to cement to increase its setting time?