The density, speed of the sound and viscosity were measured for solutions containing equimolar concentrations of
the ternary mixtures consists of Pyridine as donor with Cyclohexanone, Acetone, Acetophenone and Ethyl methyl
ketone as an acceptors separately in n-hexane solvent including pure liquids at 303K. Acoustical and
thermodynamic parameters like acoustical impedance (Z), sound velocity (U), internal pressure (πi), Intermolecular
free length (Lf) and adiabatic compressibility (ß), Formation Constant (K) have been evaluated. The constant values
of free energy of formation (ΔG#) and relaxation time () indicates that the formation of similar type of complexes
in these systems. The variation in free energy of formation (ΔG0F) values suggests that their thermodynamic stability
depends on the structure of donor and acceptor.