Maintaining Air Quality Starting Check · G3 Combined Science Chemistry

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Which statement about the air is correct?

Dry air is about 78% nitrogen and 21% oxygen, and carbon monoxide and sulfur dioxide are atmospheric pollutants.
Dry air is about 78% oxygen, and argon is an atmospheric pollutant.
Dry air is about 21% nitrogen, and nitrogen dioxide is not a pollutant.
Dry air is mainly carbon dioxide, and ozone is never a pollutant.

Which row correctly matches each pollutant to a source?

Carbon monoxide: incomplete combustion; nitrogen oxides: lightning; sulfur dioxide: volcanoes
Carbon monoxide: volcanoes; nitrogen oxides: incomplete combustion; sulfur dioxide: lightning
Carbon monoxide: incomplete combustion; nitrogen oxides: volcanoes; sulfur dioxide: car engines
Carbon monoxide: lightning; nitrogen oxides: car engines; sulfur dioxide: incomplete combustion

Which pair of effects is correct?

Carbon monoxide reduces oxygen transport in the blood; sulfur dioxide and nitrogen dioxide form acid rain that damages buildings and irritates the lungs.
Carbon monoxide forms acid rain; sulfur dioxide binds to haemoglobin.
Carbon monoxide destroys the ozone layer; nitrogen dioxide causes global warming.
Carbon monoxide is harmless; sulfur dioxide only affects plants.

Which statement about the carbon cycle is correct?

Respiration and combustion add carbon dioxide, photosynthesis removes it, and the balance keeps the atmospheric level fairly steady.
Photosynthesis adds carbon dioxide, and respiration removes it.
Combustion removes carbon dioxide, so burning more fuel lowers its level.
The level of carbon dioxide is fixed and cannot change.

Which statement about greenhouse gases is correct?

Carbon dioxide from burning fossil fuels and methane from cattle may contribute to global warming, causing more extreme weather.
Sulfur dioxide from volcanoes is the main greenhouse gas and causes ozone depletion.
Nitrogen and oxygen trap heat and cause polar ice to grow.
Methane removes carbon dioxide and cools the Earth.

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Why can deforestation increase atmospheric carbon dioxide even if the trees are not immediately burned?

Less photosynthesis removes less $\ce{CO2}$
Less respiration removes less $\ce{CO2}$
More ozone produces $\ce{CO2}$
Nitrogen changes directly into $\ce{CO2}$

Two emission reports list P: lightning and hot internal combustion engines; Q: volcanic activity and burning sulfur-containing fuels. Which pollutant pairing is supported?

P: sulfur dioxide; Q: nitrogen oxides
P: nitrogen oxides; Q: sulfur dioxide
P: nitrogen oxides; Q: carbon monoxide
P: carbon monoxide; Q: sulfur dioxide

Which source–pollutant–effect chain is correct?

Incomplete combustion → $\ce{CO}$ → reduced oxygen transport in blood
Complete combustion → $\ce{CO}$ → acid rain
Lightning → $\ce{CH4}$ → ozone depletion
Volcanoes → unburned hydrocarbons → increased oxygen transport

Which chain correctly explains acid rain downwind of a sulfur-containing-fuel power station?

Sulfur dioxide emission → acidic substances in atmospheric water → lower-pH rain
Nitrogen emission → methane formation → alkaline rain
Carbon monoxide emission → more blood oxygen → acidic rain
Noble-gas emission → sulfur formation → lower-pH rain

A data table gives annual mean atmospheric carbon dioxide concentrations of 316.9 ppm in 1960, 369.7 ppm in 2000 and 414.2 ppm in 2020. Which statement gives both the 1960–2020 change and a correct greenhouse explanation?

It rose by 97.3 ppm; additional carbon dioxide can enhance warming by absorbing outgoing infrared radiation
It rose by 97.3 ppm; additional carbon dioxide causes warming by letting more incoming visible sunlight through
It rose by 414.2 ppm; additional carbon dioxide can enhance warming by absorbing outgoing infrared radiation
It rose by 97.3 °C; additional carbon dioxide can enhance warming by absorbing outgoing infrared radiation

Which statement distinguishes a normal air component from an air pollutant?

A gas becomes a pollutant when present in an amount that causes harm
Every gas in dry air is automatically a pollutant
Only solid substances can be pollutants
Nitrogen gas and nitrogen oxides always have identical effects

Incomplete combustion is most likely when:

There is a plentiful supply of oxygen
There is a limited supply of oxygen
The fuel is renewable
The fuel is separated by distillation

Gas Q is released by incomplete combustion and is poisonous. Which gas is Q?

Carbon monoxide
Carbon dioxide
Methane
Ozone

A dry-air table gives nitrogen 78.0%, oxygen 20.9%, argon 0.9% and carbon dioxide 0.04%. Which conclusion is supported?

Carbon dioxide makes up the whole rounded remainder
The values prove nitrogen and oxygen reacted during measurement
Nitrogen and oxygen are the two major constituents, with nitrogen nearly four times as abundant as oxygen
Oxygen is the largest constituent because it supports combustion

What is the approximate composition of dry air by volume?

78% nitrogen and 21% oxygen
78% oxygen and 21% nitrogen
50% nitrogen and 50% oxygen
99% carbon dioxide and 1% oxygen

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Atmospheric $\ce{CO2}$ increases while the combustion rate is unchanged. Which change could explain the increase?

A decrease in photosynthesis
An increase in photosynthesis
A decrease in respiration
More carbon dioxide being removed from air

Why can an internal-combustion engine produce nitrogen oxides even when its fuel contains no nitrogen?

The high cylinder temperature allows nitrogen and oxygen from the intake air to react.
Every hydrocarbon molecule contains nitrogen that is released during combustion.
Nitrogen oxides are formed by condensation of water vapour in the exhaust.
The catalytic converter creates nitrogen oxides from carbon dioxide at low temperature.

Which pollutant is most directly linked to acid rain formation from burning fossil fuels?

$\ce{CO2}$
$\ce{SO2}$
$\ce{H2}$
$\ce{Ar}$

A blocked air inlet makes a fuel-fired heater burn incompletely. Which chain is correct?

Insufficient oxygen → carbon monoxide → reduced oxygen transport in blood → stop use and repair the air supply
Insufficient oxygen → nitrogen → improved blood oxygen → keep using the heater
Blocked inlet → methane → more photosynthesis → plant trees indoors
Carbon monoxide → incomplete combustion → blocked inlet → no control needed

How can a higher greenhouse-gas concentration enhance the natural greenhouse effect?

The natural greenhouse effect disappears when gas concentration rises
More outgoing infrared radiation is absorbed and re-emitted, initially reducing energy loss to space and causing warming
The gases create energy from nothing
All incoming sunlight is permanently blocked

Instrument P dries an air sample; instrument Q includes 2.0% water vapour. Q reports a smaller nitrogen percentage. What is the best explanation?

Nitrogen reacts completely with water vapour
Dry air must contain exactly 2.0% water vapour
Q proves oxygen replaced nitrogen
Water vapour increases the stated total, so nitrogen can be a smaller percentage without being removed

Incomplete combustion of methane can produce carbon monoxide. Which is a balanced equation?

$\ce{2CH4 + 3O2 -> 2CO + 4H2O}$
$\ce{CH4 + 2O2 -> CO + 2H2O}$
$\ce{CH4 + O2 -> CO2 + H2O}$
$\ce{CH4 + O2 -> C + 2H2O}$

Which product is most directly linked to incomplete combustion of a hydrocarbon?

$\ce{CO2}$
$\ce{CO}$
$\ce{O2}$
$\ce{H2}$

Which gases make up most of the small remainder after nitrogen and oxygen in dry air?

Noble gases and carbon dioxide
Hydrogen and chlorine
Methane and sulfur dioxide
Carbon monoxide and ammonia

A dry-air sample contains 77.8% nitrogen and 21.1% oxygen. Which interpretation is strongest?

The values are consistent with approximate dry-air composition
The sample must be pure oxygen
The missing fraction proves all carbon dioxide escaped
Nitrogen and oxygen have exchanged identities

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Maintaining Air Quality Starting Check · G3 Combined Science Chemistry

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