Question

carbon dioxide slightly toxic, odorless, colorless gas needed by plants for photosynthesis. the fact of the matter: the mass of a plant is primarily carbon which comes from carbon dioxide. write or doodle: what are 2 natural and 2 manmade sources of carbon dioxide?

Explanation:

To answer the question about natural and man - made sources of carbon dioxide, we analyze common sources:

• Natural sources:
• Respiration: All living organisms (plants, animals, and microorganisms) respire. During respiration, glucose ($C_6H_{12}O_6$) is broken down in the presence of oxygen to release energy, and carbon dioxide ($CO_2$) is a by - product. The chemical equation for aerobic respiration is $C_6H_{12}O_6 + 6O_2

ightarrow6CO_2+6H_2O + energy$.

• Decomposition: When organic matter (like dead plants, animals, or waste) decomposes, bacteria and fungi break down the organic compounds. This process also releases carbon dioxide. For example, when a tree falls and starts to decay, the decomposers break down the cellulose and other organic materials in the tree, producing $CO_2$.
• Man - made sources:
• Burning of fossil fuels: Fossil fuels such as coal, oil, and natural gas are rich in carbon. When we burn them for energy (in power plants, vehicles, etc.), the carbon in the fossil fuels combines with oxygen to form carbon dioxide. The combustion of coal, for instance, can be represented as $C + O_2

ightarrow CO_2$ (for complete combustion).

• Deforestation and land - use change: When we cut down forests (for agriculture, urbanization, etc.), the trees that were absorbing carbon dioxide through photosynthesis are removed. Also, when the cleared land is used for activities like burning (to clear the land for farming), it releases large amounts of carbon dioxide.

Answer:

Natural sources of $CO_2$:

1. Respiration (by living organisms like animals, plants, and microbes).
2. Decomposition (of dead organic matter by decomposers like bacteria and fungi).

Man - made sources of $CO_2$:

1. Burning of fossil fuels (such as coal, oil, and natural gas in power plants, vehicles, etc.).
2. Deforestation (cutting down trees and burning of cleared vegetation).