The half-life of a reaction is a measure of the time it takes for the concentration of a reactant to decrease by half.
The relationship between the half-life and the order of a reaction can be expressed mathematically as:
\(t_{1/2} \propto \frac{1}{{[A]}^{(n-1)}}\)
where \(t_{1/2}\) is the half-life,\( [A] \) is the initial concentration of the reactant, and n is the order of the reaction.
Given that the half-life is inversely proportional to the fifth power of the initial concentration, we can rewrite the equation as:
\(t_{1/2} \propto \frac{1}{{[A]}^5}\)
Comparing this equation with the general form, we can see that \(n - 1 = 5\), which implies that n = 6.
Therefore, the order of the reaction is (C) 6.