DP Physics (last assessment 2024)

Question 20N.2.HL.TZ0.6a(i)

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.2.HL.TZ0.6a(i)
Level	HL	Paper	2	Time zone	TZ0
Command term	State	Question number	a(i)	Adapted from	N/A

a(i).

[Maximum mark: 1]

20N.2.HL.TZ0.6a(i)

One possible fission reaction of uranium-235 (U-235) is

${}_{92}^{235}U + {}_{0}^{1}n \to {}_{54}^{140}{Xe} + {}_{38}^{94}{Sr} + 2 {}_{0}^{1}n$

Mass of one atom of U-235 $= 235 u$
Binding energy per nucleon for U-235 $= 7.59 MeV$
Binding energy per nucleon for Xe-140 $= 8.29 MeV$
Binding energy per nucleon for Sr-94 $= 8.59 MeV$

(a(i))

State what is meant by binding energy of a nucleus.

[1]

Markscheme

energy required to «completely» separate the nucleons
OR
energy released when a nucleus is formed from its constituent nucleons ✓

Allow protons AND neutrons.

Examiners report

Generally, well answered but candidates did miss the mark by discussing the constituents of a nucleus rather than the nucleons, or protons and neutrons. There seemed to be fewer comments than usual about 'the energy required to bind the nucleus together'.

Syllabus sections

Core

Core » Topic 7: Atomic, nuclear and particle physics » 7.2 – Nuclear reactions

Core » Topic 7: Atomic, nuclear and particle physics

Question 20N.2.HL.TZ0.6a(i)

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