Felspar Decomposition Reaction Analysis

This question asks to identify the correct chemical equation representing the decomposition of a substance related to felspar under the influence of carbon dioxide and water.

Identifying Key Reaction Products

The reaction involves a hydrated potassium aluminate-like compound ($K_2Al_2O_3.6H_2O$) reacting with carbon dioxide ($CO_2$) and water ($nH_2O$). Based on the provided options and common geological weathering processes, the expected products are:

• Potassium carbonate ($K_2CO_3$), formed from the potassium ($K$) component and carbon dioxide ($CO_2$).
• A hydrated aluminum silicate, which is a type of clay mineral.
• Silica ($SiO_2$), often in a hydrated form.

Analyzing Option A

Option A presents the following products:

Let's break down these products:

• Potassium Carbonate: $K_2CO_3$
• Hydrated Aluminum Silicate: $Al_2O_3.2SiO_2.2H_2O$. This formula is an oxide representation of kaolinite ($Al_2Si_2O_5(OH)_4$), a common product of felspar weathering.
• Hydrated Silica: $4SiO_2.nH_2O$, representing excess silica released during decomposition.

This set of products aligns with the typical outcome of felspar decomposition reactions involving carbonic acid, where potassium is leached as a carbonate, and the remaining aluminosilicate structure breaks down into clay minerals and silica.

Therefore, Option A correctly represents the characteristic products of such a decomposition process.