MCAT General Chemistry Question 273: Answer and Explanation

Home > MCAT Test > MCAT general chemistry practice tests

Test Information

Question: 273

5. All of the following are true regarding the earth’s atmosphere EXCEPT:

  • A. the boundary between the atmosphere and outer space is indistinct.
  • B. the ozone layer is primarily composed of ozone gas.
  • C. more than 3.75 × 1018 kg of atmospheric gases is contained within an 11 km distance from the earth's surface.
  • D. water vapor contributes to warmer atmospheric temperatures.

Correct Answer: B

Explanation:

B The passage states that the limit between outer space and the atmosphere is not definite, so choice A is a true statement. The passage also states that the mass of the atmosphere is 5 × 1018 kg, and 75 percent of this (3.75 × 1018 kg) is 11 km from the surface of the earth. Therefore, choice C is also a true statement. Water vapor was listed as a greenhouse gas in the last paragraph, thus choice D is a true statement. Although the majority of ozone is located in the ozone layer, the passage states that concentrations of ozone are 2–8 ppm. To be the primary component, concentrations would have to exceed 500,000 ppm. Choice B is a false statement and therefore the correct answer.

Previous       Next