Answer:
8.0 s.
Explanation:
Hello,
In this, case, by knowing that the half-life time allows as to compute the rate constant in terms of the initial concentration as shown below:
Therefore, the fourth half-life time implies that the concentration is 1/16 the initial one, therefore:
That is analyzed considering that if the initial concentration is 1M the first half-time is at 0.5M, the second at 0.25M, the third at 0.125M and the fourth at 0.0625M which is 16 times smaller than 1M.
Best regards.