DP Physics (first assessment 2025)

Question 20N.2.HL.TZ0.10c

Date	November 2020	Marks available	[Maximum mark: 2]	Reference code	20N.2.HL.TZ0.10c
Level	HL	Paper	2	Time zone	TZ0
Command term	Show that	Question number	c	Adapted from	N/A

[Maximum mark: 2]

20N.2.HL.TZ0.10c

(c)

Experiments with many nuclides suggest that the radius of a nucleus is proportional to $A^{\frac{1}{3}}$ , where $A$ is the number of nucleons in the nucleus. Show that the density of a nucleus remains approximately the same for all nuclei.

[2]

Markscheme

volume of a nucleus proportional to ${(A^{\frac{1}{3}})}^{3} = A$ AND mass proportional to $A$ ✓

the ratio $\frac{mass}{volume}$ independent of $A$ «hence density the same for all nuclei» ✓

Both needed for MP1

Examiners report

This question proved challenging and it wasn't common to find answers that scored both marks. Of those that had the right approach some missed out on both marks by describing A as the mass of the nucleus rather than proportional to the mass of the nucleus.

Syllabus sections

E. Nuclear and quantum physics » E.1 Structure of the atom

Question 20N.2.HL.TZ0.10c

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