The molecular formula of feldspar is

Options

A. `K_(2)O.Al_(2)O_(3).6SiO_(2)`
B. `K_(2)O.3Al_(2)O_(3).6SiO_(2)`
C. `Na_(3)AlF_(6)`
D. `CaSO_(4).2H_(2)O`

Answer

To determine the molecular formula of feldspar, we can follow these steps:

### Step 1: Identify the Types of Feldspar
Feldspar is a group of minerals that includes various types, such as potash feldspar and soda feldspar. The two most common types are:

- Potash Feldspar (Orthoclase): KAlSi3O8
- Soda Feldspar: NaAlSi3O8

### Step 2: Understand the General Formula
The general formula for feldspar can be represented as:
- For potash feldspar: K2O.Al2O3.6SiO2
- For soda feldspar: Na2O.Al2O3.6SiO2

### Step 3: Identify the Correct Molecular Formula
From the information provided, we can see that the molecular formula for feldspar can be represented as:
- Na2O.Al2O3.6SiO2

This indicates that feldspar contains sodium oxide (Na2O), aluminum oxide (Al2O3), and silicon dioxide (SiO2).

### Step 4: Conclusion
Thus, the molecular formula of feldspar is:
**Na2O.Al2O3.6SiO2**