Strategies for solving questions related to chemical thermodynamics and enthalpy changes in the chemistry section of the JEE Main exam:

1. Understand the concepts:
- Start by thoroughly understanding the basic concepts of thermodynamics, including enthalpy, entropy, Gibbs free energy, and the laws of thermodynamics.
- Familiarize yourself with the various types of enthalpy changes, such as enthalpy of formation, combustion, and reaction.
- Understand the sign conventions for enthalpy changes (endothermic and exothermic processes).

2. Review relevant equations and formulas:
- Make sure to review and understand the relevant equations and formulas related to chemical thermodynamics, such as the equation for calculating enthalpy change (∆H = H products - H reactants).
- Familiarize yourself with the standard enthalpy of formation (∆H°f) values for common compounds, as they are often used in thermodynamics calculations.

3. Practice numerical problems:
- Solve a variety of numerical problems to gain proficiency in applying the concepts and equations.
- Practice calculating enthalpy changes using Hess's law and calorimetry.
- Solve problems involving phase changes, heat transfer, and thermodynamic cycles.

4. Pay attention to units and conversions:
- Be mindful of the units used in the given data and the required answer.
- Convert units if necessary to ensure consistency and accuracy in calculations.

5. Understand the relationship between enthalpy changes and other thermodynamic quantities:
- Learn how to relate enthalpy changes to other thermodynamic quantities, such as entropy and Gibbs free energy.
- Understand the concept of spontaneity and the conditions under which a reaction or process is favored based on the sign of ∆H, ∆S, and ∆G.

6. Analyze the given problem:
- Carefully read and understand the problem statement, identifying the key information and what is being asked.
- Identify the relevant concepts and equations that can be applied to solve the problem.

7. Organize your approach:
- Plan your solution by breaking down the problem into smaller steps.
- Write down the given information, known values, and equations that can be applied.
- Clearly show your calculations and units to avoid mistakes.

8. Check your answer:
- Review your solution and check if it logically and mathematically makes sense.
- Verify that your answer has the correct units and significant figures.

9. Practice time management:
- Since the JEE Main exam has a time limit, practice solving problems within the given time frame.
- Develop a systematic approach to quickly identify the relevant concepts and equations for each problem.

10. Revise and clarify:
- After solving problems, review the concepts and equations to ensure a deeper understanding.
- Clarify any doubts or misconceptions by referring to textbooks, study materials, or seeking guidance from teachers or mentors.