Problem

In a zero-order reaction, the rate is constant and independent of concentration—it depends only on the rate constant $k$. The key insight is that the half-life formula for zero-order reactions, $t_{1/2} = \frac{[A]_0}{2k}$, depends directly on the initial concentration. When you reduce $[A]_0$ to one-quarter, the half-life shrinks proportionally, so you need to find how this change affects the time to reach 50% completion.

In a zero-order reaction, the rate is constant and independent of concentration—it depends only on the rate constant $k$. The key insight is that the half-life formula for zero-order reactions, $t_{1/2} = \frac{[A]_0}{2k}$, depends directly on the initial concentration. When you reduce $[A]_0$ to one-quarter, the half-life shrinks proportionally, so you need to find how this change affects the time to reach 50% completion.