Match the following : 

	List – I		List – II
A	Zeroth law of thermodynamics	I	Direction of flow of heat
B	First law of thermodynamics	II	Work done is zero
C	Free expansion of a gas	III	Thermal equilibrium
D	Second law of thermodynamics	IV	Law of conservation of energy

A. Zeroth law of thermodynamics → III. Thermal equilibrium
The Zeroth law states that if two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. This principle is the foundation for the concept of temperature.

B. First law of thermodynamics → IV. Law of conservation of energy
The First law states that the total energy in an isolated system is constant. Energy can be transformed from one form to another (e.g., from heat to work), but it cannot be created or destroyed. This is essentially the law of conservation of energy.

C. Free expansion of a gas → II. Work done is zero
In a free expansion, a gas expands into a vacuum without doing work on the surroundings because there is no opposing force.

D. Second law of thermodynamics → I. Direction of flow of heat
The Second law of thermodynamics states that heat naturally flows from a body at a higher temperature to a body at a lower temperature, and not the other way around, which defines the direction of heat flow.