c
\(2 C_{6} H_{5} C O O H \rightarrow\left(C_{6} H_{5} C O O H\right)_{2}\)

Before association \(1\) mole

After association \(1-x \quad x / 2\)

Total \(=1-x+\frac{x}{2}=1-\frac{x}{2}\)

\(\therefore i=\frac{1-x / 2}{1}\)

or, \(i=1-\frac{x}{2}\)