Which substance found in fossil fuels can form a harmful acid when the fuel is burned?

Answer is: sulfur.

Fossil fuel combustion increases the acidity of rain because the sulfur dioxide is produced.  

Because of fuel combustion, sulfur dioxide goes up into the atmosphere as the hot gases rise, than it reacts with water and oxygen in the air and form sulfuric acid:  

Balanced chemical reaction: SO₂(g) + 2O₂(g) + 2H₂O → 2H₂SO₄.  

pH (potential of hydrogen) is a numeric scale used to specify the acidity or basicity an aqueous solution.

When pH is less than seven (pH<7), solution is acidic.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.