MC test: Environmental impact – global warming

Multiple choice test on C.5 Environmental impact – global warming

Use the following 'quiz' to test your knowledge and understanding of this sub-topic. As this relates to a sub-topic on the options you may need access to the IB data booklet.

If you get an answer wrong, read through the explanation carefully to learn from your mistakes.

Which are greenhouse gases?

I. H2O(g)

II. CCl2F2(g)

III. CH4(g)

All three are significant greenhouse gases. Dichlorodifluoromethane is often better known for its ozone depleting ability but it is also a potent greenhouse gas with a GWP of over 8000. Although not listed on the IB syllabus it could be deduced that it is a greenhouse gas as its dipole moment will change during stretching and bending vibrations.

 

Observations from Mauna Loa show that the concentration of carbon dioxide in the atmosphere is now about 407 ppm. What is the percentage of carbon dioxide in the atmosphere?

407 parts per million 4.07 x 10−4 parts of the atmosphere which is 4.07 x 10−2 expressed as a percentage.

 

Nitrogen, oxygen and argon are the three most abundant gases in the atmosphere.  Which explain why none of these three gases is a greenhouse gas?

I. They do not allow the passage of incoming short-wave radiation from the sun

II. None of their molecular vibrations involve a change in dipole moment.

III. They do not absorb infrared radiation.

They do allow the passage of short-wave radiation from the sun (otherwise there would be no life on Earth!) but they do not absorb infrared radiation as none of their vibrations involve a change in dipole moment.

 

Sulfur hexafluoride, SF6, is about 24000 times better than carbon dioxide at absorbing and re-radiating infrared radiation. Why does it only account for a very small amount  (<0.2%) of the total amount of global warming caused by greenhouse gases.

Sulfur hexafluoride is only present in the atmosphere in very low concentrations although measurements at Mauna Loa show that its concentration increased from 4 parts per trillion to 7.5 ppt during the period 1998 - 2011. Its production and use is now very tightly controlled.

 

Which effects caused by global warming will cause sea levels to rise?

I. thermal expansion of water

II. increased melting of polar ice caps

III. retreat of glaciers

Melting of land based ice (in glaciers or the polar caps) increases the volume of sea water as does raising the temperature of sea water itself.

 

Which vibration that occurs in molecules of carbon dioxide will be infrared inactive?

The only one that does not involve a change in dipole moment is symmetrical stretching and so it will not be IR active.

 

There is a heterogeneous equilibrium between the concentration of atmospheric carbon dioxide and aqueous carbon dioxide in the oceans. Which equation best describes this heterogeneous equilibrium?

Carbon dioxide dissolved in water does not dissociate completely into H+ ions and CO32− as it does not form a strong acid. The equation  CO2(aq) + H2O(l) ⇆ H2CO3(aq) is a homogeneous equilibrium and CO2(aq) does not describe the state (or phase) of carbon dioxide in the atmosphere

 

Which equation best describes the current destruction of coral reefs caused by an increase in ocean acidity?

Ocean acidity is mainly caused by an increase in dissolved carbon dioxide and coral is essentially composed of solid calcium carbonate. 

 

Which describe how clouds can interact with radiation in the atmosphere?

I. They can reflect some of the incoming short-wave radiation from the sun.

II. They can radiate infrared radiation out to space.

III. They can absorb some of the radiated infrared radiation from the Earth's surface

Clouds can absorb and re-radiate infrared radiation back to Earth and out to space. They can also reflect incoming radiation from the sun so helping to keep the Earth cool. The precise affect clouds have on global warming is still not clear.

 

When used in English sequestration means ”the action of taking legal possession of assets”. What does sequestration mean in the context of global warming?

Carbon capture and storage (CCS) is a technology that can capture and store up to 90% of carbon dioxide emissions from the combustion of fossil fuels. It is also known as carbon sequestration.

 

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