Acetylene is thermodynamically unstable and readily explodes, therefore it is stored in commercial cylinders used for oxy-acetylene torch for welding. These cylinders contain:

Options

A. (a) Pumice stone saturated with acetone.
B. (b) Charcoal powder saturated with acetone.
C. (c) Dissolved in water to give `0.5M` solution.
D. (d) Dissolved in turpentine oil.

Answer

To answer the question regarding what is contained in commercial cylinders used for storing acetylene, we can follow these steps:

### Step 1: Understand the properties of acetylene
Acetylene (C2H2) is a colorless gas that is highly flammable and can be explosive under certain conditions. Due to its instability, it cannot be stored in its pure gaseous form.

**Hint:** Remember that acetylene is unstable and can be dangerous if not stored properly.

### Step 2: Identify safe storage methods
To safely store acetylene, it is typically dissolved in a solvent. This prevents the gas from reaching explosive concentrations and helps stabilize it.

**Hint:** Think about what materials can safely dissolve gases and prevent them from being explosive.

### Step 3: Recognize the common storage medium
The most common method for storing acetylene is to dissolve it in acetone. Acetone is a solvent that can hold a significant amount of acetylene gas, allowing it to be stored safely in cylinders.

**Hint:** Recall that acetone is a common solvent used in various applications, including the storage of gases.

### Step 4: Identify the material used in the cylinders
In addition to acetone, the cylinders themselves often contain a porous material, such as pumice stone, which is saturated with acetone. This provides a larger surface area for the acetylene to dissolve in, enhancing safety.

**Hint:** Consider what types of materials can be used to increase the surface area for gas absorption.

### Step 5: Review the options given in the question
The options provided in the question include:
- Pumice stone saturated with acetone
- Charcoal powder saturated with acetone
- Dissolved in water to give a 0.5 M solution
- Dissolved in turbidite oil

From our understanding, the correct answers are:
- **Pumice stone saturated with acetone** (Option A)
- **Dissolved in water to give a 0.5 M solution** (Option C)

**Hint:** Eliminate options that do not align with the common practices for storing acetylene.

### Final Answer
The commercial cylinders used for storing acetylene contain:
- Pumice stone saturated with acetone (Option A)
- Dissolved in water to give a 0.5 M solution (Option C)