class 6 air around us

In 1774, Joseph Priestly showed that air contains oxygen gas

Composition of Air

Nitrogen – 78%
Oxygen – 21%
Argon – 0.9 %
Carbon dioxide – 0.01%
Varying quantities of dust, smoke, water vapour
During burning of any substance, oxygen is used up and Carbon di oxide is given out
The amount of water vapour in air varies from place to place and time to time
Amount of water vapour in air is known as Humidity
Coastal areas are rich in humidity Ex: Mumbai
The amount of dust particles in air varies from place to place and time to time
Dust in air are harmful to our respiratory system
Fine hair, mucus in nostrils prevent the dust from entering into our respiratory system
Process of breathing in, getting energy from food and breathing out is called as Respiration
Humans and most animals breathe in oxygen through Nose and goes into our lungs
Living things in soil breathe oxygen from soil
Animals living in water breathe in dissolved oxygen
Solubility of air reduces as the temperature goes up
Plants have small openings called Stomata on upper sides of leaves
Tape grass breathe in oxygen through their body surface
Nitrogen is required by plants for their growth
Nitrogen in air is brought to Earth in the form of Nitric acid through Lightening and rain.
Microorganism in soil convert them into Nitrate compounds which are absorbed by plants
Nitrogen in air is used to make fertiliser for plants
Plants use carbon di oxide for preparing its food and gives out oxygen for the entire living organism to the world
The percentage of oxygen in air remain same even after respiration and burning. This is because of photosynthesis process
The Natural cycle of consumption of oxygen for respiration and burning and oxygen release by photosynthesis process is called Oxygen cycle
Oxygen cycle is affected by excessive burning of fossil fuels and deforestation

USES OF AIR:

Air helps to rotate windmills which in turn generate electricity
Birds, Insect, aeroplanes, balloons, parachute, fly and work because of air
Air helps in the dispersal of seeds, pollination and water cycle
Atmosphere is responsible for weather changes
Blowing of storms and cyclones are due to the movement of air
Water vapour in the air is responsible for snowfall and rainfall
The atmosphere act as a blanket and help Earth’s surface to maintain the right temperature
The upper atmosphere contains a layer of gas called Ozone
Ozone filters out the harmful UV rays from the sun that can cause eye problems and skin cancer

Contamination of air by undesirable substances is known as Pollutants

Main Pollutants of air are Minute dust particles Dust, Smoke
Harmful gases carbon monoxide, Oxides of sulphur and Nitrogen from fuel in vehicles. Factories, home
Air pollution can cause number of respiratory problems such as asthma , cough etc.