Question

Kaolin mainly consists of

• A. Magnesium silicate
• B. Aluminium silicate
• C. Magnesium phosphate
• D. Aluminium phosphate

Hint:

Kaolin is composed mainly of aluminium silicate and is commonly used in ceramics and pharmaceuticals.

Answer 1

The Correct Option is B

Kaolin's active mineral component is kaolinite, a hydrated aluminium silicate formed by the natural weathering of aluminosilicate rocks like feldspar. Magnesium silicate describes talc instead, and the two phosphate options belong to an entirely different chemical family with no connection to clay minerals. So the composition being asked for is aluminium silicate.

Answer 2

We can also confirm this by thinking about kaolin's pharmaceutical uses, which follow directly from its aluminosilicate chemistry.

1. Magnesium silicate: This compound (as in talc) is used mainly as a dusting powder and glidant, a different pharmaceutical role from kaolin's adsorbent use.
2. Aluminium silicate: Kaolin's fine, plate-like aluminium silicate particles give it a large adsorptive surface area, which is why it is used medicinally as an intestinal adsorbent (for diarrhoea) and in cosmetic/dermatological dusting powders and poultices.
3. Magnesium phosphate: Phosphate salts of this kind are used in entirely different contexts, such as antacid or nutritional formulations, not as clay-type adsorbents.
4. Aluminium phosphate: Likewise, this is a distinct phosphate compound used in different pharmaceutical contexts, not the mineral basis of kaolin.

Kaolin's characteristic adsorbent pharmaceutical use traces directly back to its aluminium silicate mineral structure.

Therefore, the correct answer is Aluminium silicate.