Atmosphere

Sample questions

Showing 10 of 70 questions from this chapter. The full bank is in the chapter test below.

1. 1

   Which pair lists the two major components of the atmosphere with their approximate percentages by volume?

   • A.✓ Nitrogen 78.00% and oxygen 21.01% (correct answer)
   • B.Oxygen 78.00% and nitrogen 21.01%
   • C.Nitrogen 21.01% and carbon dioxide 78.00%
   • D.Oxygen 21.01% and argon 78.00%

   Why: Dry air is dominated by nitrogen (78.00%) and oxygen (21.01%). Argon (0.93%) and carbon dioxide (0.04%) are only minor components, so any pair that gives them a major share is wrong.
2. 2

   Which of the following pairs are minor components of the atmosphere?

   • A.Methane and hydrogen
   • B.Helium and krypton
   • C.✓ Argon and carbon dioxide (correct answer)
   • D.Neon and xenon

   Why: Argon (0.93%) and carbon dioxide (0.04%) are the minor components. Methane, hydrogen, neon, helium, krypton and xenon occur only in trace amounts.
3. 3

   In which order do the four layers of the atmosphere occur when moving outward from the earth's surface?

   • A.Stratosphere, troposphere, mesosphere, thermosphere
   • B.✓ Troposphere, stratosphere, mesosphere, thermosphere (correct answer)
   • C.Troposphere, mesosphere, stratosphere, thermosphere
   • D.Thermosphere, mesosphere, stratosphere, troposphere

   Why: With increasing altitude the layers are troposphere (up to 12 km), stratosphere (12-50 km), mesosphere (50-80 km) and thermosphere (80-600 km).
4. 4

   The lowest layer of the atmosphere extends from the ground up to a height of about:

   • A.600 km
   • B.80 km
   • C.50 km
   • D.✓ 12 km (correct answer)

   Why: The troposphere is the lowest layer and reaches to about 12 km. The values 50 km, 80 km and 600 km are the upper limits of the stratosphere, mesosphere and thermosphere.
5. 5

   How does the temperature change with increasing altitude within the troposphere?

   • A.✓ It falls regularly from about 17 °C to -58 °C (correct answer)
   • B.A regular rise from about -58 °C to -2 °C is observed
   • C.It falls regularly from about -2 °C to -93 °C
   • D.A steady value of about 17 °C is maintained throughout

   Why: Temperature in the troposphere decreases steadily from roughly 17 °C at ground level to -58 °C at the top. The fall from -2 °C to -93 °C belongs to the mesosphere, and the rise from -58 °C to -2 °C to the stratosphere.
6. 6

   The stratosphere lies between 12 km and 50 km above the earth's surface. What is the thickness of this layer?

   • A.12 km
   • B.✓ 38 km (correct answer)
   • C.50 km
   • D.62 km

   Why: Thickness = 50 km - 12 km = 38 km. The values 12 km and 50 km are the lower and upper boundaries, not the thickness.
7. 7

   Which statement correctly describes the temperature trend in the stratosphere?

   • A.It falls from 17 °C to -58 °C with increasing altitude
   • B.A fall from -2 °C to -93 °C occurs with increasing altitude
   • C.A rise from 500 °C to 2000 °C occurs with increasing altitude
   • D.✓ It rises from about -58 °C to -2 °C with increasing altitude (correct answer)

   Why: Temperature increases with altitude through the stratosphere, from about -58 °C at its base to -2 °C at its top, because ozone absorbs ultraviolet radiation and releases heat there.
8. 8

   The stratosphere is divided into three regions according to the:

   • A.density of the gases present in each region
   • B.direction of the prevailing winds in each region
   • C.✓ distribution of ultraviolet radiation coming from the sun (correct answer)
   • D.quantity of particulate matter suspended in each region

   Why: The three regions of the stratosphere are distinguished by how much ultraviolet radiation passes through them: ozone breakdown dominates in the upper region, ozone formation in the middle, and the lower region receives too little UV for either.
9. 9

   Which equation represents the formation of ozone in the middle stratosphere?

   • A.$\ce{O3 (g) -> O2 (g) + O (g)}$
   • B.✓ $\ce{O2 (g) + O (g) -> O3 (g)}$ (correct answer)
   • C.$\ce{3O2 (g) -> 2O3 (g)}$
   • D.$\ce{O2 (g) + O2 (g) -> 2O (g)}$

   Why: Ozone is formed when diatomic oxygen combines with monoatomic oxygen: $\ce{O2 (g) + O (g) -> O3 (g)}$. The first equation is the ultraviolet-driven breakdown of ozone, not its formation.
10. 10

    The combination of monoatomic oxygen with diatomic oxygen to form ozone releases heat. What does this heat explain about the stratosphere?

    • A.✓ Temperature increases with altitude in the stratosphere (correct answer)
    • B.Temperature decreases with altitude in the stratosphere
    • C.Ozone is formed only in the lowest part of the layer
    • D.Monoatomic oxygen disappears in the middle of the layer

    Why: The recombination $\ce{O2 (g) + O (g) -> O3 (g)}$ is exothermic, and the energy released warms the layer, which is why temperature rises with altitude in the stratosphere.