Question

What happens if the percentage of oxygen in the air reaches $70 \%$?

Answer 1

Hint: Anything that takes up space is matter. The presence of air in our lives is unavoidable. The atmosphere is a blanket of air that covers the earth. It is the most essential of the few fundamental elements since no existence can survive for more than a fraction of a second without it. It is needed for the survival of all organisms.

Complete answer:
The atmosphere of the Earth is made up of a mixture of gases called air. Since these molecules are colourless and odourless, we can only sense them rather than see them. These gases form an ocean in the atmosphere. It is made up of 78 percent nitrogen, 21% oxygen, and 1% other gases and water vapour. The amount of moisture in the air varies depending on where you are. In comparison to wetlands, arid areas have lower moisture content.
Oxygen is needed for combustion and is consumed during the process. As oxygen reacts chemically with another substance, energy is released; this is referred to as burning or oxidation. Any reactive element, when mixed with another element or chemical, will produce a flame if it releases enough heat.
${\text{ Fuel }} + {{\text{O}}_2} \to {\text{C}}{{\text{O}}_2} + {{\text{H}}_2}{\text{O}}$
It is very simple to distinguish the combustion reaction from the general combustion reaction because oxygen and carbon dioxide are often present on the reactant side, and water vapours and heat are generated.
Oxygen serves as an oxidizer in the combustion phase, allowing it to continue. If the percentage of oxygen in the air exceeds $70\%$, any material that catches fire would be impossible to extinguish because oxygen promotes combustion.

Note:
Oxygen is a chemical element with the atomic number 8 and the letter O. It is a highly reactive nonmetal and an oxidising agent that readily forms oxides with certain elements and other compounds. It belongs to the chalcogen group of the periodic table. By mass, oxygen is the third most abundant element in the universe, behind hydrogen and helium. Two atoms of the element join together at normal temperature and pressure to form dioxygen, a colourless and odourless diatomic gas.