BEST IELTS Academic Reading Test 32
ACADEMIC READING TEST 32 – PASSAGE – 3
ACADEMIC READING TEST 32
READING PASSAGE – 3
You should spend about 20 minutes on Question. 27-40 which based on Reading Passage 3 below:
The ozone layer in a layer in Earth atmosphere, which contains relatively high concentrations of ozone (03) This layer absorbs93-99% of the sun’s high frequency ultraviolet light, which is potentially damaging m life on earth. Over 91% of ozone in earth’s atmosphere is present here. “Relatively high” means a few parts per million— much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 10 km to 50 km above Earth’s surface, though the thickness varies seasonally and geographically. The ozone layer was discovered in 1913 by the French physicists Chubs Fabry and Henri buisson. Its properties were explored at detail by the British meteorologist G. M. A Dobson, who developed a simple spectrophometer that could he used to measure stratospheric ozone from the ground. Between 1928 and 1958 Dobson established worldwide network of ozone monitoring stations which continues to operate today (2008). The “Dobson unit”, a convenient measure of the total amount of ozone in a column overhead is named in his honour.
The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930. Ozone in the earth’s stratosphere is created by ultraviolet light spiking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic, oxygen); the atomic oxygen then combines with unbroken O2to create ozone, O3. The ozone molecule is also unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O2 and an atom of atomic oxygen, a continuing process called the ozone-oxygen cycle thus creating an ozone layer in the stratosphere, the region from about 10 to 50 km (32,000 to 164,000 feet) above Earth’s surface. A bend 90% of the ozone in our atmosphere is contained in the stratosphere. Ozone concentrations are greatest between about 20 and 40 km. where they range about 2 to 8 parts per million. If all of the ozone were compressed to the pressure of the air to the sea level, it would be only a few millimetres thick.
Ten percent of ozone in the atmosphere is contained in the troposphere, the lowest part of our atmosphere where all of our weather takes place, Troposphere ozone has two sources, about 10% is transported down from the stratosphere while the remainder is created in smaller amounts through different mechanisms.
Although the concentration of the ozone in the ozone layer Is very small, it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation emitted bat, the Sun UV radiation is divided into three categories based on its wavelength, these are referred to as UV-A, UV-B, and UV-C, which would be very harmful to humans, is entirely screened out by ozone to around 35 km altitude. UV-B radiation can be harmful to the skin and is the main causes unborn; excessive exposure can also cause genetic damage, as a result, problems such as skin cancer. The ozone layer is very effective at screening out UV-B; for radiation with a wavelength of 290 nm, the intensity at Earth’s surface is 350 billion time, weaker than at the top of the atmosphere. Nevertheless, some UV-B reaches the surface. Most UV-A reaches the surface, this radiation is significantly less harmful, although it can potentially cause genetic damage.
Depletion of the ozone layer allows more of the UV radiation. And particularly the more harmful wavelengths, to reach the surface, causing increased genetic damage to living creatures and organisms.
Fill in the blanks. Write NO MORE THAN THREE WORDS for each answer.
27. Ozone layer is the name given to layer having……………of O3.
28. Concentration of the Ozone is ……………… than in lower atmosphere.
29. Thickness of Ozone layer changes……………….
30. G. M. D Dobson described the……………. of ozone layer.
31. “Dobson unit is a name given to measure of the total amount if Ozone honour of ……………………….
CHOOSE the appropriate Letter A-D and write it in boxes 32-37 on your answer sheet.
32. Ozone in atmosphere is created by
B. Ultraviolet light
C. oxygen atoms
D. oxygen molecules
33. The addition of atom oxygen with oxygen molecules leads to
A. O2 atom
B. O2 molecule
C. O3 molecule
D. None of the above
34. Troposphere contains
A. 10% of ozone
B. 90% of ozone
C. 20% of ozone
D. None of the above
35. Ozone absolutes
A. Infrared rays
B. UV rays
D. C ϒ-rays
36. Excessive exposure to UV. β can cause
A. skin reaction
B. skin cancer
D. genetic damage
37. Give suitable title for passage
A. Earth’s atmosphere
B. Life and Ozone
C. UV rays of sun
D. Ozone layer
Do the following statements agree with the information in Reading Passage 2?
In boxes 38-40 on your answer sheet write
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN: if there is no information on this in the passages
38. Ozone is mainly located in troposphere.
39. Cause of ozone layer was found in 1930.
40. Oxygen cycle can be used to create oxygen artificially on earth’s atmosphere.
27. high consultation
28. much higher
29. seasonally and geographically
31. G. M. B. Dobson