Instead of "supercritical", you can say "gas" for N_{2}.

35bar and 0°C is a boiling condition for CO_{2}. At equilibrium, you would have a partial pressure of 35bar CO_{2} vapour in the gas phase, to which a partial pressure of N_{2} gas adds, so equilibrium is impossible.

The out-of-equilibrium proportions depend on the process and are more difficult to determine. If for instance CO_{2} is fully liquefied at 35bar and 0°C and you add N_{2} at 35bar and 0°C too, then liquid CO_{2} will stay at the bottom and gaseous N_{2} on the top, but CO_{2} evaporates slowly (without boiling if the pressure exceeds the liquid-vapour equilibrium pressure) and the total pressure rises above 35bar, for instance towards 70bar if the volume is constant.

"Superfluid" has a different meaning.