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Core practice questions

71 questions from the epa 608 certification practice test.

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Core practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

Why do HCFCs do less damage to the ozone layer than CFCs?

  1. The hydrogen in the molecule lets it break down lower in the atmosphere
  2. The fluorine in the molecule cancels out the effect of the chlorine atoms
  3. HCFC molecules are too heavy to rise above the troposphere
  4. HCFC molecules contain bromine in place of the chlorine
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A. The hydrogen in the molecule lets it break down lower in the atmosphere

Hydrogen makes an HCFC molecule less stable, so most of it breaks down before reaching the stratosphere and less chlorine arrives there. Fluorine does not neutralize chlorine, and molecular weight does not keep refrigerants out of the stratosphere.

Reference: EPA Section 608 Core

Chlorine from CFCs reaches the stratosphere, while most chlorine from natural sources such as sea spray does not. What is the main reason?

  1. CFCs are lighter than air, so they rise much faster than natural chlorine does
  2. CFCs are released at high altitude, well above the clouds and the rain
  3. CFCs are stable and do not dissolve in water, so rain does not wash them out
  4. CFCs carry far more chlorine per molecule than any natural source does
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C. CFCs are stable and do not dissolve in water, so rain does not wash them out

CFCs do not break down or dissolve in water in the lower atmosphere, so they survive long enough to drift up to the stratosphere. Natural chlorine compounds are water soluble and are rained out. CFCs are actually heavier than air; mixing by winds carries them up.

Reference: EPA Section 608 Core

After a chlorine atom breaks apart an ozone molecule in the stratosphere, what happens to the chlorine atom?

  1. It is used up and can do no further harm to ozone
  2. It bonds with nitrogen and falls back to earth
  3. It turns into fluorine and stays in the stratosphere
  4. It is freed again and goes on to destroy more ozone
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D. It is freed again and goes on to destroy more ozone

Chlorine acts as a catalyst: it is released again after each reaction, so a single atom can destroy many thousands of ozone molecules. It is not consumed in the reaction.

Reference: EPA Section 608 Core

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