Carbon monoxide is prepared by

Options

A. heating formic and with conc. `H_(2)SO_(4)`
B. heating potassium ferrocyanide with conc `H_(2)SO_(4)`
C. heating malonic acid with `:P_(2)O_(10)`
D. hydrolysis of `Mg_(2)C_(3)`

Explanation

To prepare carbon monoxide, we can consider the following methods based on the information provided:

### Step-by-Step Solution:

1. **Heating Formic Acid with Concentrated H2SO4:**
- When formic acid (HCOOH) is heated with concentrated sulfuric acid (H2SO4), it undergoes dehydration to produce carbon monoxide (CO) and water (H2O).
- The reaction can be represented as:
\[ \text{HCOOH} \xrightarrow{\text{H}_2\text{SO}_4} \text{CO} + \text{H}_2\text{O} \]
- Thus, this method is a valid way to prepare carbon monoxide.

2. **Heating Potassium Ferrocyanide with Concentrated H2SO4:**
- When potassium ferrocyanide (K4[Fe(CN)6]) is heated with concentrated sulfuric acid, it decomposes to produce carbon monoxide along with other products.
- The reaction can be represented as:
\[ \text{K}_4[\text{Fe(CN)}_6] \xrightarrow{\text{H}_2\text{SO}_4} \text{K}_2\text{SO}_4 + \text{FeSO}_4 + \text{(NH}_4)_2\text{SO}_4 + \text{CO} \]
- Therefore, this method is also a valid way to prepare carbon monoxide.

3. **Heating Malonic Acid with P2O10:**
- When malonic acid is heated with phosphorus pentoxide (P2O10), it does not produce carbon monoxide; instead, it leads to the formation of carbon dioxide (C2O3).
- Thus, this method is incorrect for the preparation of carbon monoxide.

4. **Hydrolysis of Magnesium Carbide (Mg2C3):**
- Hydrolyzing magnesium carbide (Mg2C3) does not yield carbon monoxide; instead, it produces propyne (C3H4).
- Therefore, this method is also incorrect for the preparation of carbon monoxide.

### Conclusion:
The correct methods for preparing carbon monoxide are:
- Heating formic acid with concentrated sulfuric acid.
- Heating potassium ferrocyanide with concentrated sulfuric acid.