Answer:
During combustion or burning, carbon from fossil fuels combine with oxygen in the air to form carbon dioxide and water vapor. These natural hydrocarbon fuels come from once-living organisms and are made from carbon and hydrogen, which release carbon dioxide and water when they burn.
<h2>Answer:</h2>
<u>Natural gas is indoor pollutant</u>
<h2>Explanation:</h2>
From the options given above smog and vehicle exhaust are outdoor pollutants. Oxygen is not a pollutant at all. The only option left is natural gas. When we cook food or use heaters we use natural gas so the burning of natural gas pollutes the indoor environment that is why we can say that natural gas is indoor pollutants.
