Answer
$0.6$ hours
Work Step by Step
Given $k=0.25, C/C_0=0.9$, we have $t=-0.25ln(1-0.9)=0.58$ hours
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.