Managing time effectively during the exam for Paper I of UPSC Chemistry Optional subject is crucial to ensure that you are able to complete the paper within the allotted time. Here are some strategies that can help you manage your time efficiently during the exam:

1. Familiarize Yourself with the Exam Pattern:
- Begin by thoroughly understanding the exam pattern, including the number of questions, marks allotted, and the time duration.
- This will help you plan your time accordingly and allocate a specific amount of time to each section or question.

2. Create a Time Allocation Plan:
- Before starting the exam, create a time allocation plan to ensure that you can cover all the questions within the given time.
- Divide the total time by the number of questions to determine the average time you should spend on each question.
- Allocate more time to questions with higher marks and less time to those with lower marks.

3. Prioritize Your Questions:
- Read through the entire question paper and prioritize the questions based on your strengths and the marks allotted to each question.
- Start with the questions you are most confident about and can answer quickly.
- This will help you build confidence and save time for more challenging questions later.

4. Manage Your Time per Question:
- Stick to the time allocation plan you created and strictly adhere to it for each question.
- If you are unable to answer a question within the allocated time, move on to the next question and come back to it later if time permits.

5. Avoid Spending Too Much Time on a Single Question:
- Do not get stuck on a difficult question for too long. If you are unsure about the answer, make an educated guess and move on.
- Remember that every question carries equal marks, so it is better to attempt all questions rather than spending excessive time on just one.

6. Use Shortcuts and Mnemonics:
- Utilize shortcuts and mnemonics to save time while solving numerical or theoretical questions.
- Practice these techniques during your preparation to become proficient in using them during the exam.

7. Review and Revise:
- Reserve some time at the end of the exam to review and revise your answers.
- Use this time to correct any mistakes, recheck calculations, and ensure that you have attempted all the questions.

By following these strategies, you can effectively manage your time during the exam for Paper I of UPSC Chemistry Optional subject. Remember to stay calm and focused, and practice time management techniques during your preparation to improve your speed and accuracy. Good luck!