Question

The first law of thermodynamics is based on the principle of:

• A. Energy conservation
• B. Entropy increase
• C. Heat transfer
• D. Irreversibility

Hint:

Remember that the First Law represents the quantity of energy (conservation), whereas the Second Law defines the quality and direction of energy flow (entropy and spontaneity).

Answer 1

The Correct Option is A

Think of a sealed system where no energy leaves or enters from outside. The first law simply says the total energy inside that system stays fixed, it can only change form between heat and work. This is nothing but the everyday idea that energy cannot appear out of nowhere or vanish, it can only be converted from one form to another. That is exactly the energy conservation principle, so the first law is really this conservation law written in equation form for heat, work and internal energy. Options about entropy or irreversibility belong to the second law, and heat transfer alone is just one term in the equation, not the principle itself. So the correct choice is energy conservation.