Chemistry 0620 · IGCSE · Air quality and climate

Air quality and climate — practice question

Carbon is found in Group IV of the Periodic Table, and it combines with oxygen to produce carbon dioxide.
(a)[1]

The energy level diagram for this reaction is shown below. Explain how the diagram indicates that the reaction is exothermic.

(b)[5]

Carbon monoxide, carbon dioxide and methane are each atmospheric pollutants. • State where these gases come from. • Describe the effects that carbon dioxide and methane have on the environment. • State one harmful effect of carbon monoxide on health.

(c(i))[1]

When calcium carbonate decomposes, calcium oxide (lime) and carbon dioxide are formed. State one use of calcium oxide.

(c(ii))[2]

Calculate the relative formula mass of calcium carbonate, $\text{CaCO}_3$. Show all your working. Your Periodic Table can help you.

(d)[3]

Carbon and magnesium are both insoluble in water. Carbon does not react with hydrochloric acid, whereas magnesium reacts to produce a soluble salt and a gas that escapes into the air. Suggest how you could prepare a pure dry sample of carbon from a mixture of carbon powder and magnesium powder.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: reactants have more energy than products / arrow points down

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