Which sodium salt will be heated with doalime to obtain propane ?

Options

A. `CH_3-CH_2-underset(O)underset(||)(C )-O-Na^(+)`
B. `CH_3-CH_2-CH_2-underset(O)underset(||)-O-Na^(+)`
C. `(CH_3)_(2)-CH-underset(O)underset(||)(C )-O-Na^(+)`
D. 2 & 3 both

Answer

To determine which sodium salt can be heated with soda lime (a mixture of sodium hydroxide and calcium oxide) to obtain propane, we need to analyze the options provided and understand the reaction mechanism involved.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
Soda lime is used in a reaction known as decarboxylation, where a sodium salt of a carboxylic acid is heated to remove carbon dioxide (CO2) and produce an alkane. In this case, we want to produce propane (C3H8).

2. **Identifying the Structure of Propane**:
Propane has the molecular formula C3H8, which can be represented structurally as CH3-CH2-CH3.

3. **Finding the Suitable Sodium Salt**:
To produce propane, we need a sodium salt of a carboxylic acid that, when decarboxylated, will yield three carbon atoms in total.

4. **Analyzing the Options**:
- If we consider the sodium salt of propanoic acid (sodium propanoate, CH3CH2COONa), upon heating with soda lime, it will lose CO2 and yield propane:
\[ CH3CH2COONa \xrightarrow{\text{soda lime}} CH3-CH2-CH3 + Na2CO3 \]
- Other sodium salts, such as sodium acetate (CH3COONa) or sodium butanoate (CH3CH2CH2COONa), will not yield propane upon decarboxylation.

5. **Conclusion**:
The sodium salt that can be heated with soda lime to obtain propane is sodium propanoate (option D).

### Final Answer:
The sodium salt that will be heated with soda lime to obtain propane is **sodium propanoate (option D)**.