Which of the following relation is incorrect?

Options

A. `a=3P_(c)V_(c)^(2)`
B. `b=V_(c)//3`
C. `T_(c)=8a//27Rb`
D. `b=3V_(c)`

Explanation

To solve the question of which relation is incorrect among the given options, we will analyze each of the provided equations based on the critical constants in the van der Waals equation.

### Step-by-Step Solution:

1. **Understanding the Critical Constants**:
- The critical constants are defined for a substance and include critical pressure (Pc), critical volume (Vc), and critical temperature (Tc). These constants are derived from the van der Waals equation.

2. **Analyzing the Given Relations**:
...