To an evacuated vessel with movable piston under external pressure of 1 atm 0.1 mole of He and 1.0 mole of an unknown compound vapour pressure 0.68 atm at `0^(@)C` are introduced Considering the ideal gas behaviour the total volume (in litre) of the gases at `0^(@)C` is close to .

Explanation

To solve the problem, we will follow these steps:

### Step 1: Understand the Components
We have two gases in the vessel:
- 0.1 mole of Helium (He)
- 1.0 mole of an unknown compound with a vapor pressure of 0.68 atm at 0°C.

### Step 2: Apply Dalton's Law of Partial Pressures
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