Question

विशिष्ट-विभक्तेः उपयोगं कृत्वा वाक्यनिर्माणं कुरुत। (4 तः 2)
अलम्
 

Hint:

When the verb अलम् (enough/stop) is used in a sentence, it typically takes the 3rd case (Instrumental) for the action being stopped or ceased.
In the sentence चिन्तया अलम् (Stop worrying), चिन्तया is in the 3rd case (Instrumental), meaning "with worrying" or "by worrying."
Another example: विवादेन अलम् (Stop arguing), where विवादेन is also in the 3rd case, indicating "with arguing" or "by arguing." So, अलम् commonly governs the Instrumental case for actions being stopped.

Answer 1

('अलम्' (enough/stop) इत्यस्य योगे तृतीया विभक्तिः भवति।)
वाक्यम्: चिन्तया अलम्। (Stop worrying.) (अथवा - विवादेन अलम्।)