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Read the following passage and answer the questions that follow ::
The atmosphere is a mixture of several gases. These are about ten chemical elements which remain permanently in gaseous form in the atmosphere under all natural conditions. Of these permanent gases, oxygen makes up about 21 percent and nitrogen about 78 percent. Several other gases, such as argon, carbon dioxide, hydrogen, neon, krypton, and xenon, comprise the remaining 1 percent of the volume of dry air. The amount of water vapour, and its variations in amount and distribution, are of extraordinary importance in weather changes. Atmospheric gases hold in suspension great quantities of dust, pollen, smoke, and other impurities which are always present in considerable, but variable amount.
The layer of the air next to the earth, which extends upward for about 16 km, is known as the troposphere. On the whole, it makes up about 75 percent of all the weight of the atmosphere. It is the warmest part or the atmosphere because most of the solar radiation is absorbed by the earth's surface, which warms the air immediately surrounding it. A steady decrease of temperature with increasing elevation is a most striking characteristic. The upper layers are colder because of their great distance from the earth's surface and rapid radiation of heat into space. The temperatures within the troposphere decrease about 3.5° per 1,000 feet increase in altitude. Within the troposphere, winds and air currents distribute heat and moisture. Strong winds, called jet streams, are located at the upper levels of the troposphere. These jet streams are both complex and widespread in occurrence. They normally show a wave-shaped pattern and move from west to east at velocities of 240 kmph, but velocities as high as 640 kmph have been noted. The influences of changing locations and strengths of jet streams upon weather conditions and patterns are no doubt considerable.
Above the troposphere to a height of about 80 km is a zone called the stratosphere. The stratosphere is separated from the troposphere by a zone of uniform temperatures called the tropopause. Within the lower portions of the stratosphere is layer of ozone gases which filters out most of the ultraviolet rays from the sun. The ozone layer varies with air pressure. If this zone were not there, the full blast of the sun's ultraviolet light would burn our skins, bl in d our eyes, and eventually result in out destruction. Within the stratosphere, the temperature and atmosphere composition are relatively uniform.
The layer upward of about 80 km is the most fascinating but the least known of these three strata. It is called ionosphere because it consists of electrically charged particles called ions, thrown from the sun. Its effect upon weather conditions, if any, is as yet unknown.
[1] It can be inferred from the passage that a jet plane will usually have its best average speed on its run form:
(a) London to New York
(b) New Delhi to Tokyo
(c) New Delhi to Washington
(d) Melbourne to New Delhi[2] This passage does not provide information about:
(a) The effect of refrigerants on ozone depletion
(b) The amount of oxygen in the atmosphere
(c) The presence of considerable waste 'products in the atmosphere
(d) The presence of permanent gases in the atmosphere[3] Which of the following questions is/are answered on the basis of information contained in the passage ?
1. How do the troposphere and the stratosphere differ?
2. How does the ionosphere affect the weather?
Select the correct answer using the code given below:
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2[4] It can be inferred from the passage that at the top of a location which is above 16,000 feet above a town, the temperature is usually:
(a) Below freezing
(b) Warmer than that in the town
(c) About 56° colder than that on the ground
(d) Affected by the ionosphere[5] Life as we know it exists on the earth because the atmosphere:
(a) Is warmest at the bottom
(b) Carries the ultraviolet rays of the sun
(c) Contains a layer of ozone gases
(d) Contains a lot of water vapours[6] The troposhere is the warmest part of the atmosphere because it:
(a) Radiates heat into space
(b) Is warmed by the earth's heat
(c) Has winds and air currents that distribute the heat
(d) Contains jet streamsasked in General Ability, 2006
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