A 10.0 L cylinder of `H_(2)` gas is connected to an evacuated 290.0 L tank. If the final pressure is 700 mm Hg, what must have been the original gas pressure in the cylinder? 

Explanation

To solve the problem, we will use the ideal gas law and the concept of gas expansion. The relationship between the initial and final states of the gas can be expressed using the formula derived from Boyle's Law, which states that for a given mass of gas at constant temperature, the product of pressure and volume is constant.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Volume of the cylinder (V1) = 10.0 L
- Volume of the tank (V2) = 290.0 L
- Final pressure (P2) = 700 mm Hg
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