`NH_(3)` and `SO_(2)` gases are being prepared at two corners of a laboratory. The gas that will be detected first in the middle of the laboratory is:

Explanation

To determine which gas, NH₃ (ammonia) or SO₂ (sulfur dioxide), will be detected first in the middle of the laboratory, we can use Graham's law of effusion. This law states that the rate of diffusion of a gas is inversely proportional to the square root of its molar mass. Here are the steps to solve the problem:

### Step-by-Step Solution:

1. **Identify the Gases**: We have two gases: ammonia (NH₃) and sulfur dioxide (SO₂).

2. **Calculate the Molar Mass of NH₃**:
- The molar mass of nitrogen (N) is 14 g/mol.
...