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List any three human activities which would lead to an increase in the carbon dioxide content of air.
(i) Burning of fuels in various processes like heating, cooking, transportation, and industry.
(ii) Human induced forest fires
(iii) The process of deforestation includes the cutting down of trees. This decreases the uptake of carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases.
What are the different states in which water is found during the water cycle?
During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water, river water, etc.), and gaseous state (water vapours).
Name two biologically important compounds that contain both oxygen and nitrogen.
Two biologically important compounds that contain both oxygen and nitrogen are:
(i) Amino acids
(ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
What are the different states in which water is found during the water cycle?
he different states in which water is found in the water cycle are solid-state, liquid state and gaseous state:
1. Water occurs in the form of water vapour in the gaseous state. It evaporates from the surface of water bodies and mixes with air(evaporation).
2. Water vapour condenses high up in the atmosphere and falls on the earth in the form of rain in a liquid state( condensation).
3. In Solid-state water is formed by the freezing of liquid droplets in the upper layer of atmosphere these droplets fall on the earth in the form of Snow hail and sleet ( called precipitation).
Name two biologically important compounds that contain both oxygen and nitrogen.
Proteins and nucleic acids (DNA and RNA) are the two biologically important compounds that contain both oxygen and nitrogen.
Nitrates (NO3-) and nitrites (NO2-) are also other biologically important compounds containing both oxygen and nitrogen, as nitrogen is absorbed by plants only in the form of NO3- and NO2-.
List any three human activities which would lead to an increase in the carbon dioxide content of air.
The following activities of human beings may increase the carbon dioxide content of air:
(i) Burning of fossil fuels such as petrol, diesel and coal in various activities like transportation and industrial processes.
(ii) Burning of wood and charcoal for heating, cooking, etc.
(iii) Deforestation that reduces the green plant and tree population, resulting in less utilisation of atmospheric CO2 during photosynthesis and it's increased content in the air.
What is the greenhouse effect?
1)The greenhouse effect is a natural process that warms the Earth’s surface.
2)When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
3 )Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs).
4)The absorbed energy warms the atmosphere and the surface of the Earth.
5) Increasing greenhouse gases in the atmosphere trap heat which is more than required, without letting it radiate back in space, this leads to global warming.
What are the two forms of oxygen found in the atmosphere?
The two forms of oxygen found in the atmosphere are:
(i) Diatomic molecular form with chemical formula O2.
(ii) Triatomic molecular form with chemical formula O3 known as ozone.
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