Strategies to effectively answer questions that require practical applications in Paper I of UPSC Chemistry Optional subject:

1. Understand the question:
- Read the question carefully and make sure you understand what is being asked.
- Identify the key components, concepts, and keywords mentioned in the question.

2. Analyze the given information:
- Analyze the given information or data provided in the question.
- Identify any relevant formulas, equations, or principles that can be applied to solve the problem.

3. Plan your approach:
- Plan a step-by-step approach to solve the problem.
- Break down the problem into smaller parts if necessary.
- Decide which principles, concepts, or theories can be applied to solve each part of the problem.

4. Apply the relevant concepts:
- Apply the relevant concepts, theories, and formulas to solve each part of the problem.
- Show all the steps of your calculations and explain the reasoning behind each step.
- Use proper units and significant figures throughout your solution.

5. Provide real-life examples:
- Whenever possible, provide real-life examples or practical applications related to the concepts being discussed.
- Explain how the concept or theory is used in real-world scenarios to solve practical problems or improve efficiency in various industries.

6. Use diagrams and illustrations:
- Use diagrams, illustrations, or graphs to visually represent the problem or solution.
- Label the components and provide a clear explanation of the significance of each element in the diagram.

7. Include relevant examples from previous years' question papers:
- Include relevant examples from previous years' question papers to support your answer and demonstrate your understanding of the subject.
- Emphasize the importance of practical applications in chemistry and how they contribute to advancements in various fields.

8. Practice previous years' question papers:
- Practice solving previous years' question papers to familiarize yourself with the type of questions asked in the exam.
- This will help you develop a better understanding of the practical application-based questions and improve your problem-solving skills.

By following these strategies, you can effectively answer questions that require practical applications in Paper I of the UPSC Chemistry Optional subject. Remember to read the question carefully, analyze the given information, plan your approach, apply the relevant concepts, provide real-life examples, use diagrams and illustrations, include examples from previous years' question papers, and practice solving similar questions.