a) Methane is a hydrocarbon fuel - Edexcel - GCSE Chemistry - Question 6 - 2020 - Paper 1

Carbon and carbon monoxide are produced in the incomplete combustion of methane due to a limited supply of oxygen. When oxygen is insufficient, not all carbon atoms are converted to carbon dioxide, leading to the formation of solid carbon (soot) and carbon monoxide (a toxic gas).

The fraction in Figure 10 that is used to surface roads is "bitumen."

The fraction in Figure 10 that contains hydrocarbons with the lowest boiling point is "gases."

The correct answer is B) gases, petrol, diesel oil.

In the cracking reaction, octane (C₈H₁₈) produces one molecule of ethane (C₂H₆) and one molecule of C₆H₋ₓ. The total number of carbon atoms must remain the same:

eight (from octane) = two (from ethane) + six (from C₆H₋ₓ).

Thus, x = 6.

To find the maximum mass of octane produced, first establish the number of moles of dodecane:

$ext{Number of moles of dodecane} = \frac{340g}{170g/mol} = 2.0 ext{ moles}$

Since one mole of dodecane yields one mole of octane, the number of moles of octane produced will equal the number of moles of dodecane:

$ext{Moles of octane} = 2.0 ext{ moles}$

The mass of octane can be calculated as follows:

$ext{Mass of octane} = \text{Moles of octane} \times \text{Molar mass of octane} = 2.0 ext{ moles} \times 114g/mol = 228g$

Therefore, the maximum mass of octane that could be produced is 228g.