DP Chemistry (last assessment 2024)

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Question 20N.3.hl.TZ0.12e

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Date November 2020 Marks available [Maximum mark: 1] Reference code 20N.3.hl.TZ0.12e
Level hl Paper 3 Time zone TZ0
Command term Outline Question number e Adapted from N/A
e.
[Maximum mark: 1]
20N.3.hl.TZ0.12e

1.57 % of the mass of a rock weighing 46.5 kg is uranium(IV) oxide, UO2. 99.28 % of the uranium atoms in the rock are uranium-238, U238.

(e)

Thorium-234 has a higher binding energy per nucleon than uranium-238. Outline what is meant by the binding energy of a nucleus.

[1]

Markscheme

energy required to separate a nucleus into protons and neutrons/nucleons
OR
energy released when nucleus was formed from «individual/free/isolated» protons and neutrons/nucleons ✔


Do not accept “energy released when atom was formed”.

Examiners report

Although many scored the one mark for outlining what is meant by the binding energy of a nucleus, the question was often answered as energy involved in the formation of an atom. Some candidates did not understand the difference between nucleus and nucleons.

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