To solve this problem, we need to use the ideal gas law equation:

PV = nRT

Where:
P = pressure of the gas
V = volume of the gas
n = number of moles of gas
R = ideal gas constant
T = temperature in Kelvin

We are given the following information:
- 9 g of charcoal is placed in a one-liter vessel containing gas at 300 K.
- The pressure of the gas decreases by 40% of the original pressure, equal to 700 millibar.
- The density of the charcoal sample is 1.5 g/cm3.

Let's break down the problem into steps:

**Step 1: Calculating the original pressure**
We are given that the pressure decreases by 40% of the original pressure, equal to 700 millibar. So, the original pressure can be calculated using the equation:

Original pressure - 0.4 * Original pressure = 700 millibar

Simplifying the equation:

0.6 * Original pressure = 700 millibar

Original pressure = 700 millibar / 0.6

Original pressure = 1166.67 millibar

**Step 2: Converting pressure to bar**
Since we are asked to find the volume of gas at 1 bar, we need to convert the pressure to bar.

1 bar = 1000 millibar

So, the original pressure is 1166.67 millibar / 1000 = 1.16667 bar.

**Step 3: Calculating the number of moles of gas**
To calculate the number of moles of gas, we need to use the ideal gas law equation. Rearranging the equation to solve for n:

n = PV / RT

Substituting the known values:

n = (1.16667 bar * 1 L) / (0.0831 bar L/mol K * 300 K)

n = 0.046 mol

**Step 4: Calculating the volume of gas adsorbed per gram of charcoal**
To calculate the volume of gas adsorbed per gram of charcoal, we need to divide the volume of gas (V) by the mass of charcoal (m).

Given that the density of the charcoal sample is 1.5 g/cm3, we can calculate the mass of charcoal:

Mass of charcoal = 9 g

Volume of charcoal = Mass of charcoal / Density of charcoal = 9 g / 1.5 g/cm3

Volume of charcoal = 6 cm3

Dividing the volume of gas (1 L) by the volume of charcoal (6 cm3):

Volume of gas adsorbed per gram of charcoal = 1 L / 6 cm3 = 1000 mL / 6 mL = 166.67 mL/g

**Step 5: Converting milliliters to liters**
To convert milliliters to liters, we divide by 1000:

Volume of gas adsorbed per gram of charcoal = 166.67 mL/g / 1000 mL/L = 0.16667 L/g

**Step 6: Calculating the final answer**
Finally, we need to multiply the volume of gas adsorbed per gram of charcoal by the mass of the given sample (9 g) to find the volume of gas at 1 bar and 273.15 K adsor