$$A \rightarrow B$$
The above reaction is of zero order. Half life of this reaction is 50 min. The time taken for the concentration of A to reduce to one-fourth of its initial value is ______ min. (Nearest integer)

We need to find the time for the concentration of A to reduce to one-fourth for a zero-order reaction with half-life of 50 min.

For zero order: $$[A] = [A]_0 - kt$$

Half-life: $$t_{1/2} = \frac{[A]_0}{2k} = 50$$ min, so $$k = \frac{[A]_0}{100}$$.

$$\frac{[A]_0}{4} = [A]_0 - kt$$

$$kt = \frac{3[A]_0}{4}$$

$$t = \frac{3[A]_0}{4k} = \frac{3[A]_0}{4 \times \frac{[A]_0}{100}} = \frac{3 \times 100}{4} = 75$$ min

The time is 75 min.

Therefore, the answer is 75.