Give scientific reasons.
(a) The danger from the greenhouse effect is rising.
(b) The proportion of nitrogen in air remains constant.
(c) When a bottle of an aerated drink is opened, the drink inside gushes out in a stream of bubbles.
Give scientific reasons.
(a) The danger from the greenhouse effect is rising.
(b) The proportion of nitrogen in air remains constant.
(c) When a bottle of an aerated drink is opened, the drink inside gushes out in a stream of bubbles.
(a) The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric gases, and is re−radiated in all directions including the surface and the lower atmosphere. This results in an elevation of the average surface temperature. The greenhouse gases are:
Water vapours: 36−70%
Carbon dioxide: 9−26%
Methane: 4−9%
Ozone: 3−7%
The level of carbon dioxide gas is rising at the rate of about one part per million per year. These carbon dioxide molecules absorb the heat energy, but do not emit the absorbed heat completely, so it increases the temperature of the Earth’s surface. Hence, danger from the greenhouse effect is rising.
(b) Due to nitrogen cycle, the proportion of nitrogen in the atmosphere remains constant.
Stages of nitrogen cycle:
• Some nitrogen fixing bacteria such as Azotobactor and Rhizobium convert the atmospheric nitrogen into nitrates that are soluble in water. This process is known as nitrogen fixation.
• During lightning nitrogen in the atmosphere reacts with oxygen to form dilute nitric acid. This acid comes down to the Earth with rain water.
• Nitrates are absorbed by plants into their system and utilized for making organic matter such as proteins.
• When animals consume plant matter, they break down the nitrogenous compounds in the plants and use them to form new animal proteins and other cell components.
• When an animal excretes urea or uric acid, or when an animal or plant dies, certain bacteria carry out ammonification. In this process the bacteria produce ammonium ions from nitrogen−containing molecules.
• Plants can assimilate these ammonium ions, or other bacteria can change it to nitrate by nitrification. Plants can absorb some of the nitrates produced in this way.
• Some micro−organisms convert ammonia into nitrates. This process is known as nitrification.
• There are some other bacteria that reduce nitrates back to nitrogen or to ammonia or to some other oxides. This process is known as denitrification.
• Free nitrogen returns back to the atmosphere and oxides are taken up by the plants.
In this way, the nitrogen cycle keeps the proportion of nitrogen constant in the atmosphere.
(c) A bottle of aerated drink is filled with carbon dioxide gas. Carbon dioxide gas is sparingly soluble in water. Hence, to dissolve carbon dioxide in water, some pressure is applied. When the cap of the bottle is opened, the pressure is released and carbon dioxide gas gushes out in the form of bubbles.
(a) The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric gases, and is re−radiated in all directions including the surface and the lower atmosphere. This results in an elevation of the average surface temperature. The greenhouse gases are:
Water vapours: 36−70%
Carbon dioxide: 9−26%
Methane: 4−9%
Ozone: 3−7%
The level of carbon dioxide gas is rising at the rate of about one part per million per year. These carbon dioxide molecules absorb the heat energy, but do not emit the absorbed heat completely, so it increases the temperature of the Earth’s surface. Hence, danger from the greenhouse effect is rising.
(b) Due to nitrogen cycle, the proportion of nitrogen in the atmosphere remains constant.
Stages of nitrogen cycle:
• Some nitrogen fixing bacteria such as Azotobactor and Rhizobium convert the atmospheric nitrogen into nitrates that are soluble in water. This process is known as nitrogen fixation.
• During lightning nitrogen in the atmosphere reacts with oxygen to form dilute nitric acid. This acid comes down to the Earth with rain water.
• Nitrates are absorbed by plants into their system and utilized for making organic matter such as proteins.
• When animals consume plant matter, they break down the nitrogenous compounds in the plants and use them to form new animal proteins and other cell components.
• When an animal excretes urea or uric acid, or when an animal or plant dies, certain bacteria carry out ammonification. In this process the bacteria produce ammonium ions from nitrogen−containing molecules.
• Plants can assimilate these ammonium ions, or other bacteria can change it to nitrate by nitrification. Plants can absorb some of the nitrates produced in this way.
• Some micro−organisms convert ammonia into nitrates. This process is known as nitrification.
• There are some other bacteria that reduce nitrates back to nitrogen or to ammonia or to some other oxides. This process is known as denitrification.
• Free nitrogen returns back to the atmosphere and oxides are taken up by the plants.
In this way, the nitrogen cycle keeps the proportion of nitrogen constant in the atmosphere.
(c) A bottle of aerated drink is filled with carbon dioxide gas. Carbon dioxide gas is sparingly soluble in water. Hence, to dissolve carbon dioxide in water, some pressure is applied. When the cap of the bottle is opened, the pressure is released and carbon dioxide gas gushes out in the form of bubbles.
