500 cm3 of hydrogen at S. T.P. contain N molecules. How many molecules are present in 25 `cm^(3)` of oxygen at S. T.P. ?

Explanation

To solve the problem, we need to determine how many molecules are present in 25 cm³ of oxygen (O₂) at standard temperature and pressure (STP), given that 500 cm³ of hydrogen (H₂) contains N molecules.

### Step-by-Step Solution:

1. **Understand STP**:
At standard temperature and pressure (STP), one mole of any gas occupies 22,400 cm³ (or mL). This means that at STP, the volume of a gas is directly proportional to the number of moles and thus the number of molecules.

2. **Given Information**:
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