DP Chemistry (last assessment 2024)

Question 20N.3.hl.TZ0.d

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.hl.TZ0.d
Level	hl	Paper	3	Time zone	TZ0
Command term	Suggest	Question number	d	Adapted from	N/A

[Maximum mark: 1]

20N.3.hl.TZ0.d

Gasoline (petrol), biodiesel and ethanol are fuels.

[U.S. Department of Energy. https://afdc.energy.gov/]

A mixture of gasoline and ethanol is often used as a fuel. Suggest an advantage of such a mixture over the use of pure gasoline. Exclude any discussion of cost.

[1]

Markscheme

Any one:

uses up fossil fuels more slowly ✔

lower carbon footprint/CO2 emissions ✔

undergoes more complete combustion ✔

produces fewer particulates ✔

higher octane number/rating
OR
less knocking ✔

prevents fuel injection system build up
OR
helps keep engine clean ✔

Accept an example of a suitable advantage even if repeated from 11c.

Examiners report

Most scored the one mark for this question, with "less knocking or higher octane number/rating" the most common correct answer seen.