Question

Explain how the balance of oxygen in the air is maintained though it is used for respiration and combustion.

Answer 1

The balance of oxygen in the air is maintained by following three processes

PRODUCTION OF OXYGEN

Photosynthesis- The process by which plants use carbon dioxide and water to form sugar(carbohydrate) and oxygen in the presence of sunlight.

$\mathrm{Carbon}\mathrm{dioxide}\left(\mathrm{g}\right)+\mathrm{Water}\left(\mathrm{l}\right)\stackrel{\mathrm{sunlight}}{\to }\mathrm{Glucose}\left(\mathrm{s}\right)+\mathrm{Oxygen}\left(\mathrm{g}\right)$

CONSUMPTION OF OXYGEN

Combustion - The reaction of oxygen with a substance(fuel) that results in the release of heat and light is called combustion.

$\mathrm{Fuel}\left(\mathrm{s}\right)/\left(\mathrm{l}\right)/\left(\mathrm{g}\right)+\mathrm{Oxygen}\left(\mathrm{g}\right)\to \mathrm{Carbon}\mathrm{dioxide}\left(\mathrm{g}\right)+\mathrm{Heat}+\mathrm{Light}$

Respiration - The process by which organisms get energy by the conversion of glucose in the presence of oxygen into carbon dioxide and water vapor.

$\mathrm{Glucose}\left(\mathrm{s}\right)+\mathrm{Oxygen}\left(\mathrm{g}\right)\to \mathrm{Carbon}\mathrm{dioxide}\left(\mathrm{g}\right)+\mathrm{Water}\mathrm{vapour}\left(\mathrm{g}\right)+\mathrm{Energy}$

THE CYCLE OF PRODUCTION AND CONSUMPTION

• The oxygen gas is produced by plants and other photosynthetic organisms on earth.
• The oxygen gas thus produced is consumed by all organisms during the process of respiration.
• The burning of wood and fossil fuels also requires oxygen.
• The carbon dioxide gas produced from respiration and combustion is again consumed during photosynthesis.
• Hence, the amount of oxygen gas remains the same in the atmosphere.