CBSE Class 12 English Unseen Passage G

Read the passage given below:

1. Did you know that world-wide monitoring has shown that the ozone in the stratosphere has declined, over the past two decades, with losses of around 10 per cent in winter and spring and around five per cent in summer and autumn in locations as diverse as Europe, Australia and North America? Are you aware that a United Nations report stated that the annual dose of harmful ultraviolet radiation striking the northern hemisphere rose by five per cent during the last decade? Or that scientists estimate that for each one per cent decline in ozone levels, human beings will suffer as much as a two to three per cent increase in the incidences of certain cancers of the skin?

2. Do any of these facts make any sense? Why should a declining ozone layer assume so much importance? Here’s why. Ozone does a wonderful job of absorbing those damaging ultraviolet rays, so harmful to man. Indeed, without this gaseous shield, harmful radiation would have undisputed access to the earth. Every year, millions of tonnes of pollutant gases are sent into the earth’s atmosphere. Some remain at low levels but some accumulate in the upper atmosphere, drastically, altering — the way the sun’s heat energy and rays pass to and from the earth.

3. Each year since the late 1970s, the stratospheric ozone above Antarctica has disappeared during September creating what is popularly known as the ozone hole. What is frightening is the fact that this Antarctic hole measures about 9 million miles — nearly the size of North America! The hole over Antarctica lasts only for two months but during this time it lets in lethal doses of ultraviolet radiation. After its stay here, the hole passes over the world’s more populated parts including Australia and New Zealand, where the ultraviolet radiation which it lets in has the potential to cause various types of skin cancer, injure the eyes, harm the immune system and upset the balance of an entire ecosystem.

4. Research on ozone and the atmosphere led to a global ban on synthetic gases of Chlorofluorocarbon (CFC) production. More than 150 countries signed what is known as the Montreal Protocol, an international agreement which called for a phased reduction in the release of CFCs. Modifications of the treaty called for a complete ban on CFCs which began in January 1996. However, even with this ban in effect, chlorine from the CFCs will continue to accumulate in the atmosphere for about a decade. All of us know that carbon dioxide, water vapour and certain other gases in the atmosphere act in trapping/absorbing the sun’s heat, which is then reflected back to the ground. This phenomenon which keeps the earth warm is known as the greenhouse effect. Without it, the rising heat would escape directly into space and we would live in much colder conditions. 

5. However, human activity has begun to alter the composition of the atmosphere. The burning of fuels such as oils in motor vehicles and coal and wood in factories and homes has led to the production of carbon dioxide and other greenhouse gases. These are increasing the greenhouse effect leading to global warming. Scientists fear that these greenhouse gases may trap so much heat that the earth could warm up by more than 4 degrees Celsius over the next 50 years. In a moving article about the Gulf War entitled The War That Wounded the World, William Thomas wrote, “California’s Lawrence Livermore laboratory had tracked smoke from the Middle East oil fires three times around the planet at altitudes exceeding 10,000 metres. Astronauts would later make headlines describing a haze-shrouded globe. As nuclear and biological arms proliferate, we must find a better way to resolve future conflicts. This wounded planet cannot absorb more lessons.”

On the basis of your understanding of the above passage, answer ANY TEN of the questions given below:

Question. Ozone ....................
(a) releases CO₂
(b) absorbs ultraviolet rays
(c) produces oxygen
(d) none of the options

Answer: B

Question. The greenhouse gases ....................
(a) may trap much heat
(b) are not detrimental
(c) lead to global warming
(d) both (a) and (c)

Answer: D

Question. Human interference has changed ....................
(a) the composition of atmosphere
(b) the shape of ozone layer
(c) the process of greenhouse
(d) none of the options

Answer: A

Question. Which word in para 5 is antonym of ‘dwindle’?
(a) Increasing
(b) Entitle
(c) Trap
(d) Proliferate

Answer: D

Question. The Montreal Protocol called for a complete ban on carbon dioxide. (True/False)
Answer: False

Question. Any transformation in the composition of atmosphere is directly linked to ....................
Answer: human activity

Question. What has the worldwide monitoring of ozone revealed?
Answer: It has revealed that ozone has declined in the stratosphere. The losses range from around ten per cent in winter and spring and around five per cent during summer and autumn. The affected areas are as widespread as Europe, Australia and North America.

Question. Why has the declining ozone layer assumed so much importance?
Answer: Ozone absorbs damaging ultraviolet rays and checks the flow of harmful radiation to the earth. The accumulation of pollutant gases in the upper atmosphere alters the passage of sun’s heat energy and rays to and from the earth.

Question. What do you learn about the ozone hole?
Answer: The stratospheric ozone above Antarctica disappears during September. The hole which lasts for two months only measures about 9 million miles—nearly the size of North America.

Question. How does the ozone hole prove harmful?
Answer: The ozone hole lets in the ultraviolet radiation which causes skin cancer, eye-injury, harm to immune system and upsets the balance of entire eco-system.

Question. How does the greenhouse effect affect human beings?
Answer: The greenhouse effect warms up the earth. It affects human beings by increasing the earth’s temperature.

Question. Find the word in para 3 which is the synonym of ‘hidden power or qualities
Answer: Potential