Question 1
Where does carbon dioxide come from?

Atmospheric carbon dioxide derives from multiple natural sources including volcanic outgassing, the combustion of organic matter, and the respiration processes of living aerobic organisms; man-made sources of carbon dioxide come mainly from the burning of various fossil fuels for power generation and transport use.

Explanation:

Carbon dioxide (CO₂) is a colourless and odourless gas that is a natural component of our air and makes up part of the carbon cycle.

Through the decomposition of organic matter, CO₂ is released into the atmosphere as part of this natural process. At the same time, photosynthesis helps to significantly reduce atmospheric CO₂ . The solubility of CO₂ in water depends on the temperature, so the oceans both produce and reduce CO₂. 

Anthropogenic (man-made) carbon dioxide sources primarily relate to the combustion processes of fossil fuels. CO₂ is an inert end product that accumulates in the atmosphere and is in constant exchange with the biosphere and the oceans. Carbon dioxide reacts with water to form carbonic acid or hydrogen carbonate, which leads to a change in the pH value, i.e. the acidity of the water. Other anthropogenic CO₂ sources that intensify the greenhouse effect include changes to land usage, e.g. the clearing of forests or draining of wetlands such as moors.

a fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.[1] the age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years.[2] fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.[3] other commonly used derivatives include kerosene and propane. fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of almost pure carbon, like anthracite coal. methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.

the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust over millions of years was first introduced by andreas libavius "in his 1597 alchemia [alchymia]" and later by mikhail lomonosov "as early as 1757 and certainly by 1763".[4] the first use of the term "fossil fuel" was by the german chemist caspar neumann, in english translation in 1759.[5]

in 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy consumption in the world.[6] non-fossil sources in 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.[7] world energy consumption was growing at about 2.3% per year. in 2015 about 18% of worldwide consumption was from renewable sources.[8]