Which among the following is a false statement ?

Options

A. `SiO_(2)` has a structure similar to that of `CO_(2)`
B. Natural Si exists only in the combined state
C. Si can be prepared by reducing `SiO_(2)` with Mg
D. Si does not exist in graphite-like structure, but exists only in diamond like structure

Explanation

To determine which among the given statements is false, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** SiO2 (silica) has a structure similar to that of CO2.

- **Analysis:**
- CO2 has a linear structure due to its double bonds between carbon and oxygen (C=O) and exhibits p-pi bonding.
- SiO2, on the other hand, has a three-dimensional network structure where silicon is bonded to oxygen in a tetrahedral arrangement.
- Silicon cannot form p-pi bonds like carbon can.

**Conclusion:** This statement is **false**.

### Step 2: Analyze the Second Statement
**Statement:** Natural silicon exists only in the combined state.

- **Analysis:**
- Silicon is highly reactive and typically found in nature combined with oxygen in the form of silicates and oxides.
- This statement implies that silicon does not exist in its elemental form in nature, which is true.

**Conclusion:** This statement is **true**.

### Step 3: Analyze the Third Statement
**Statement:** Silicon can be prepared by reducing silica (SiO2) with magnesium.

- **Analysis:**
- Silica (SiO2) can indeed be reduced by magnesium, which acts as a reducing agent.
- The reaction produces silicon and magnesium oxide (MgO), confirming silicon's reduction from +4 oxidation state in SiO2 to 0 in elemental silicon.

**Conclusion:** This statement is **true**.

### Step 4: Analyze the Fourth Statement
**Statement:** Silicon does not exist in a graphite-like structure but exists only in a diamond-like structure.

- **Analysis:**
- Silicon typically forms a diamond cubic structure, which is similar to the arrangement in diamond.
- Silicon cannot form a graphite-like structure because it does not have the ability to form p-pi bonds with itself, which is necessary for the layered structure of graphite.

**Conclusion:** This statement is **true**.

### Final Conclusion
After analyzing all the statements, the only false statement is the **first statement**: "SiO2 has a structure similar to that of CO2."

### Summary of Steps:
1. Analyze the structure of SiO2 and CO2.
2. Confirm the natural state of silicon.
3. Verify the reduction of SiO2 by magnesium.
4. Assess the structural forms of silicon.