Atmosphere and the Air

Which of the following shows the correct approximate composition of gases in clean and dry air?

• 78% oxygen, 21% nitrogen, 1% noble gases and carbon dioxide

• 78% nitrogen, 21% oxygen, 1% noble gases and carbon monoxide

• 78% nitrogen, 21% oxygen, 1% noble gases and carbon dioxide

• 78% oxygen, 21% noble gases and carbon dioxide, 1% nitrogen

An 80 cm³ sample of air is trapped in a syringe. The air is slowly passed over heated iron in a tube until there is no further decrease in volume.

When cooled to its original temperature, which volume of gas remains?

• 80 cm³

• 64 cm³

• 20 cm³

• 16 cm³

Select the air pollutants matched with their correct source.

• carbon monoxide - incomplete combustion of fuel in motor vehicles

• sulfur dioxide - burning of sulfur-containing fuels in power stations

• methane - sunlight acting on unburnt hydrocarbons and nitrogen oxides

• oxides of nitrogen - combination of nitrogen and oxygen in air at high temperatures in power stations

Select the air pollutants matched with their correct natural source.

• carbon monoxide - forest fires

• sulfur dioxide - lightning activity

• oxides of nitrogen - volcanic activity

• methane - bacterial decay of vegetation

Select the air pollutants matched with their correct harmful effects.

• carbon monoxide - reacts with haemoglobin in blood and prevents blood from absorbing oxygen

• sulfur dioxide - greenhouse gas which contributes to global warming

• oxides of nitrogen - reacts with oxygen and water vapour dissolve in rainwater to form acid rain

• ozone - irritates people's eyes, chests and throats and causes asthma attack

• unburnt hydrocarbon - produce ozone when react with oxides of nitrogen

Why is acid rain harmful to the environment?

Which statements / equations are true of flue gas desulfurisation?

• Sulfur dioxide produced in power stations can be treated by calcium carbonate and calcium oxide.

• CaCO₃ → CaO+CO₂

• CaSO₃ + CO₂ → CaCO₃ + SO₂

• CaO + SO₂ → CaSO₃

• Calcium sulfite can be easily oxidised to form calcium sulfate to be dumped.

Select the reaction that does not take place in the catalytic converters.

• NO and NO₂ → N₂

• CO₂ → CO

• unburnt hydrocarbons + O₂ → CO₂ + H₂O

• 2NO + 2CO → N₂ + 2CO₂

Arrange the statements in order to explain how the ozone layer is depleted.

A: Ozone layer is destroyed.

B: CFCs released rise into the upper atmosphere.

C: Chlorine atoms react with ozone layer.

D: CFCs are decomposed by sunlight to form chlorine atoms.

• D, C, B, A

• D, B, C, A

• B, D, C, A

• B, C, D, A

Which statements are true of greenhouse gases?

• Carbon dioxide and methane are examples of greenhouse gases.

• In high concentrations, they trap excessive amount of heat in the atmosphere.

• They contribute acid rain.

• They contribute to global warming.

• Ozone is an example of greenhouse gases.