According to the passage, ultraviolet radiation from the Sun

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions that follow.

Although only a small percentage of the electromagnetic radiation that is emitted by the Sun is ultraviolet (UV) radiation, the amount that is emitted would be enough to cause severe damage to most forms of life on Earth were it all to reach the surface of the Earth. Fortunately, all of the Sun’s ultraviolet radiation does not reach the Earth because of a layer of oxygen, called the ozone layer encircling the Earth in the stratosphere at an altitude of about 15 miles above the Earth. The ozone layer absorbs much of the Sun’s ultraviolet radiation and prevents it from reaching the Earth.

Ozone is a form of oxygen in which each molecule consists of three atoms (O3) instead of the two atoms (O2) usually found in an oxygen molecule. Ozone forms in the stratosphere in a process that is initiated by ultraviolet radiation from the Sun. UV radiation from the Sun splits oxygen molecules with two atoms into free oxygen atoms, and each of these unattached oxygen atoms then joins up with an oxygen molecule to form ozone. UV radiation is also capable of splitting up ozone molecules; thus, ozone is constantly forming, splitting, and reforming in the stratosphere. When UV radiation is absorbed during the process of ozone formation and reformation, it is unable to reach Earth and cause damage there.

Recently, however, the ozone layer over parts of the Earth has been diminishing. Chief among the culprits in the case of the disappearing ozone, those that are really responsible, are the chlorofluorocarbons (CFCs). CFCs meander up from Earth into the stratosphere, where they break down and release chlorine. The released chlorine reacts with ozone in the stratosphere to form chlorine monoxide (CIO) and oxygen (O2). The chlorine then becomes free to go through the cycle over and over again. One chlorine atom can, in fact, destroy hundreds of thousands of ozone molecules in this repetitious cycle, and the effects of this destructive process are now becoming evident.

According to the passage, ultraviolet radiation from the Sun..............

• A. is causing severe damage to the Earth's ozone layer
• B. is only a fraction of the Sun's electromagnetic radiation
• C. creates electromagnetic radiation
• D. always reaches the Earth

• Câu 2: Mã câu hỏi: 36763

  The word “encircling” in paragraph 1 is closest in meaning to…………….

  • A. attacking
  • B. raising
  • C. rotating
  • D. surrounding

• Câu 3: Mã câu hỏi: 36765

  It is stated in the passage that the ozone layer……………

  • A. enables ultraviolet radiation to reach the Earth
  • B. reflects ultraviolet radiation
  • C. shields the Earth from a lot of ultraviolet radiation
  • D. reaches down to the Earth

• Câu 4: Mã câu hỏi: 36766

  The pronoun “it” in paragraph 2 refers to……………….

  • A. radiation
  • B. process
  • C. formation
  • D. damage

• Câu 5: Mã câu hỏi: 36768

  The word “culprits'' in paragraph 3 is closest in meaning to which of the following?

  • A. guilty parties
  • B. detectives
  • C. group members
  • D. leaders

• Câu 6: Mã câu hỏi: 36769

  According to the passage, what happens after a chlorine molecule reacts with an ozone molecule?

  • A. The ozone breaks down into three oxygen atoms.
  • B. Two different molecules are created.
  • C. The two molecules combine into one molecule.
  • D. Three distinct molecules result.

• Câu 7: Mã câu hỏi: 36770

  The paragraph following the passage most likely discusses……….........

  • A. the negative results of the cycle of ozone destruction
  • B. where chlorofluorocarbons (CFCs) come from
  • C. the causes of the destruction of ozone molecules
  • D. how electromagnetic radiation is created