Practice MCQ Questions and answers on Chemistry-GK

The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere.

Air is mixture of different types of gases therefore it also shows the property of gases like Nitrogen and Oxygen.

Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.

It's a mixture of different gases. The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen.

Below a height of about 86 kilometers, the three main gaseous elements, which together account for about 99.9% of the total atmosphere, exist in essentially constant proportion to the total: nitrogen comprises 78% of air by volume, oxygen comprises 21% of air by volume, and argon comprises another 0.9%.

The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen.

Air is said to be saturated when the amount of water vapour in the air is the maximum possible at an existing temperature and pressure. Air is said to be saturated at 100 percent relative humidity when it contains the maximum amount of moisture possible at that specific temperature.

For extinguishing fire, we use Carbon Dioxide.

Dry powder fire extinguishers contain Sand and sodium bicarbonate.

Dry ice, carbon dioxide in its solid form, a dense, snow like substance that sublimes (passes directly into the vapour without melting) at −78.5 °C (−109.3 °F), used as a refrigerant, especially during shipping of perishable products such as meats or ice cream.