Answer: 6,987,000 pounds fo CO₂ per kWh.
Explanation: Quilowatt-hour (kWh) is a unit of energy that measures the amount of energy expended in 1 hour.
The AC uses 850 Watts, which in kW is 850,000 kW
If you leave the AC on for 6 hours, it will consume
850,000(6) = 5,100,000 kWh
Eletricity produces 1.37 pounds of CO₂ per kWh, then in 5,100,000 kWh:
1.37
.(5,100,000kWh) = 6,987,000 pounds
If you open a window for 6 hours, you would keep 6,987,000 pounds of CO₂ for entering the atmosphere.