Read the following passage carefully and answer the questions on it. We are today faced with a great ecological problem for which we are largely responsible. The planet Earth, the only home of man is bathed in a steady rain of the sun's rays. Most of these rays supply us heat and light, but a small percentage is deadly. These are the ultraviolet- B rays (or UV -B). If these were to get to the surface of the earth directly, they would kill us off. Luckily, the earth's surface is shielded from these rays by the ozone layer; but sadly enough this ozone layer is being destroyed by man. The ozone layer is formed from a kind of oxygen with three atoms ( \(O_{3}\) ) instead of the normal two (\(O_{2}\) ). Ozone occurs naturally in the stratosphere, several kilometres above the earth's surface. It absorbs the dangerous UV-B rays but allows the much needed and safe light to pass through. There in the stratosphere, it is constantly being created by the sun's rays; thus it is a self-repairing shield. But man is now gradually destroying this vital shield with his industrial gases. The most lethal of these gases are the chlorofluorocarbon, or CFC, which are used in making all kinds of foamed plastic products, propellants in spray cans, coolants in air conditioners and refrigerators and solvents to clean electronic equipment. Down here, they are not lethal. But after they have leaked from air conditioners, plastic foam, cups, etc, they slowly drift up to the stratosphere where, bombarded by ultraviolet rays, they break up at last, releasing chlorine,the real ozone killer. Sadly, one chlorine molecule may remain active for a century, destroying thousands of ozone molecules. (a) What is the greatest ecological problem which man faces today? (b)(i) What is the ozone layer made of? (ii) Where is it normally found? (c) Describe the importance of the ozone layer. (d) How is man destroying the ozone layer? (e) Give the name of a gas specifically mentioned as very dangerous to the ozone layer. (f) What kind of figurative expression is: The planet, Earth, the only home of man, is bathed in a steady rain of the sun's rays? (g) hi are used in making all kinds of foamed plastic products (i) What grammatical name is given to this expression? (ii) What is its function in the sentence? (h) For each of the following words, find another word or phrase that means the same and can replace it as used in the passage: (i) shielded (ii) absorbs (iii) vital (iv) lethal; (v)active.
Explanation
(a) The greatest ecological problem which man faces today is the exposure of earth to ultra violet rays of the sun. (b) (i) Ozone layer is made up of 'a kind of oxygen with three atoms. (ii) Ozone layer is normally found in the stratosphere. (c) The Ozone layer protects the earth from the ultra violet sun rays. (d) Man destroys the Ozone layer through industrial gases. (e) Chlorine (f) Metaphor (g)(i) adjectival or relative clause (ii) It qualifies the noun "Chlorofluorocarbons" or "CFCs." (h)(i) shielded - protected. prevented shaded. covered (ii) absorbs - Takes in (iii) vital - Beneficial, important, essential (iv) lethal - dangerous, deadly, damaging destructive (v) active - strong, powerful, functioning
