Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

Explanation

To solve the problem of how much oxygen gas is needed to react completely with 3 g of hydrogen gas, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Mass Ratio**:
The problem states that hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. This means that for every 1 gram of hydrogen, 8 grams of oxygen are required.

2. **Set Up the Relationship**:
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