* not completed

. The average molar mass of the Earth's lower atmosphere is approximately:

32 g mol^-1 correct incorrect

29 g mol^-1 correct incorrect

18 g mol^-1 correct incorrect

14 g mol^-1 correct incorrect

16 g mol^-1 correct incorrect

* not completed

. The stratopause occurs at an altitude of approximately:

15 km correct incorrect

35 km correct incorrect

50 km correct incorrect

85 km correct incorrect

500 km correct incorrect

* not completed

. With rising altitude in the stratosphere:

The temperature decreases while the pressure increases correct incorrect

Both the temperature and pressure decrease correct incorrect

The temperature increases while the pressure decreases correct incorrect

Both the temperature and pressure increase correct incorrect

The temperature is relatively constant while the pressure decreases correct incorrect

* not completed

. The energy associated with visible light of wavelength 300 nm is:

400 kJ mol^-1 correct incorrect

3600 kJ mol^-1 correct incorrect

6.6 x 10^-19 kJ mol^-1 correct incorrect

6 x 10^-18 kJ mol^-1 correct incorrect

1200 kJ mol^-1   correct incorrect

* not completed

. Which of the following statements is/are true? (Please select all that apply)

In the stratosphere, absorption of UV radiation by ozone causes it to dissociate into O₂* and O* correct incorrect

IR radiation from the Earth is absorbed by CO₂ and H2O in the troposphere correct incorrect

In the mesosphere, high energy radiation causes dissociation of dinitrogen and dioxygen molecules to form nitrogen and oxygen atoms correct incorrect

In the thermosphere, there is sufficient energy to cause dinitrogen and dioxygen molecules to lose an electron and become positive species correct incorrect

The chemical composition of the troposphere varies with the temperature profile correct incorrect

* not completed

. For a photochemical reaction, the rate constant depends on: (Please select all that apply)

The absorption cross section correct incorrect

The half-life correct incorrect

The radiative flux correct incorrect

The quantum yield correct incorrect

The wavelength of the radiation correct incorrect

* not completed

. Regarding the hydroxyl radical, which of the following statements is/are true? (Please select all that apply)

Ozone is an intermediate in hydroxyl radical formation correct incorrect

Both ground state and excited state oxygen atoms take part in hydroxyl radical formation correct incorrect

Hydroxyl radical reactions with gaseous water are important in an unpolluted atmosphere correct incorrect

Hydroxyl radicals are responsible for the formation of peroxy radicals in the atmosphere correct incorrect

Hydroxyl radicals commonly bring about abstraction of hydrogen atoms from organic molecules correct incorrect

* not completed

. The concentration of nitrogen dioxide in an urban atmosphere is measured to be 85 ppbv. Assuming P° and 20°C, this is the same as:

85 mmol m^-3 correct incorrect

85 μg m^-3 correct incorrect

8.5x10^-8 expressed as mole ratio correct incorrect

3.5x10^-6 mol m^-3 correct incorrect

1.8x10^-6 mol m^-3 correct incorrect

* not completed

. Which of the following atmospheric species is/are free radicals? (Please select all that apply)

O₃ correct incorrect

N₂O correct incorrect

NO correct incorrect

Cl₂ correct incorrect

NO₂^- correct incorrect

* not completed

. Which of the following statements about the reaction of 2NO(g) → N₂(g) + O₂(g) is/are true? (Please select all that apply)

The rate of the reaction is defined as k[NO]² correct incorrect

The half-life of the reaction is defined as t_1/2 = ln2 /k correct incorrect

The reaction is thermodynamically spontaneous at 298 K correct incorrect

The reverse reaction is extremely fast at 298 K correct incorrect

The reaction is a second order reaction correct incorrect