  We calculate the self diffusion coefficients $D_S$ for the species $s=1,2$ of
a mixture, and show that a general scaling relation $D_2{\sim}D_1^a$ with a non
universal exponent $a$ holds. The generalized diffusion coefficients, dependent
on the mass ratio $\kappa=m_2/m_1$ of the constituent particles of the mixture,
are computed using a proper formulation of the self-consistent mode coupling
theory(MCT). The present model for the dense mixture includes nonlocal and
nonlinear effects within the adiabatic approximation of fast decay of momentum
fluctuations compared to the density fluctuations. The dependence of the slow
dynamics near the characteristic ergodicity-nonergodicity (ENE) transition of
the MCT on $\kappa$ is also studied and a reentrant behavior of of $D_1$ with
respect to $D_2$, in agreement with simulations is obtained.
