Furnace exhaust and airecondition unit

No it is not. If there is a short in the ac unit there could be an explosion because of the hot gases. Also the hot gases could be going into your house from the ac unit.

The exhaust from a furnace is not combustable, its already been burned in the heat exchanger, also the condenser unit does not put outside air into the home. The only thing is, you don't want condensation from the vent dripping on the unit, as it is corrosive and can rust out your units coil. You don't use an ac unit while your using the gas furnace anyway, so the vent can be terminated close to the condenser, just not right on top of it.

Exhaust can pe-purge unburt fuel wich is flameable /explosive.

Exhaust can pe-purge unburnt fuel wich is flameable /explosive.