Answer
The third largest interplanar spacing is $a_0 / \sqrt{5}=0.4472 a_0$.
Work Step by Step
The third largest interplanar spacing is $a_0 / \sqrt{5}=0.4472 a_0$.
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.