  We study the effects of the equation of state on the nuclear suppression of
heavy flavours in quark gluon plasma and estimate the initial entropy density
of the system produced at the highest RHIC energy. For this purpose we have
used the experimental data on the charged particle multiplicity and the nuclear
suppression of single electron spectra originating from the semi-leptonic
decays of open charm and beauty mesons. We have used inputs from lattice QCD to
minimize the model dependence of the results. We obtain the value of the
initial entropy density which varies from 20 to 59 /fm$^3$ depending on the
value of the velocity of sound that one uses for the analysis. Our
investigation leads to a conservative value of the initial entropy density
$\sim 20/$fm$^3$ with corresponding initial temperature $\sim 210$ MeV well
above the value of the transition temperature predicted by lattice QCD.
