Question

one day, cars may run on fuel cells. fuel cells obtain energy from the synthesis of gaseous water from hydrogen and oxygen. if all cars switched from burning fossil fuels to fuel cells, which might you expect to also occur?
a an increase in the price of gasoline
b an increase in carbon dioxide emissions
c an increase in the number of gas stations
d an increase in the water vapor content of earths atmosphere

Explanation:

Fuel cells produce water vapor as a by - product. If all cars switch to fuel cells from fossil fuels (which produce carbon dioxide), the water vapor content in the atmosphere is likely to increase. Option A: An increase in gasoline price is not directly related to the switch to fuel cells. Option B: Fossil fuel burning produces $CO_2$, so switching to fuel cells would decrease $CO_2$ emissions. Option C: With fuel cells, the need for gas stations (for gasoline) would decrease, not increase. So the correct option is D.

Answer:

D. an increase in the water vapor content of Earth's atmosphere