CAIE A-Level Physics AS 11.1 Atoms Nuclei and Radiation Questions

Practise using scattering evidence, nuclear notation, isotopes and conservation laws to explain the nucleus and alpha, beta and gamma decay.

Exam points

infer nuclear size, charge and mass concentration from alpha-scattering results and describe the nuclear atom
use nucleon/proton numbers, isotopes and A Z X notation to determine nuclear composition and charge
apply conservation of charge and nucleon number to alpha- and beta-decay equations
describe alpha, beta-minus, beta-plus and gamma radiation, including antiparticles, neutrinos and energy spectra
use the unified atomic mass unit u in nuclear and particle contexts

Covered syllabus points

11.1.1—The results of the α-particle scattering experiment the existence and small 11.1.2—A simple model for the nuclear atom to include protons, neutrons and orbital 11.1.3—Nucleon number and proton number 11.1.4—Isotopes are forms of the same element with different numbers of neutrons in 11.1.5—The notation A Z X for the representation of nuclides 11.1.6—Nucleon number and charge are conserved in nuclear processes 11.1.7—The composition, mass and charge of α-, β- and γ-radiations (both β–11.1.8—An antiparticle has the same mass but opposite charge to the corresponding 11.1.9—That (electron) antineutrinos are produced during β– decay and (electron)11.1.10—Α-particles have discrete energies but that β-particles have a continuous 11.1.11—Α- and β-decay by a radioactive decay equation of the form UT h92 238 90 234 11.1.12—The unified atomic mass unit (u) as a unit of mass

[Maximum number: 1]

Which statement about the alpha-particle scattering experiment provides evidence for the existence of the nucleus?

A tiny proportion of the alpha-particles are deflected through large angles.

Slower alpha-particles are deflected through larger angles.

The kinetic energies of the deflected alpha-particles are unchanged.

The number of alpha-particles deflected depends on the thickness of the foil.

[Maximum number: 7]

(a)

Describe the structure of an atom of uranium-238, $\stackrel{238}{92} \mathrm{U}$ .

[ 2 ]

(b)

The decay of uranium-238 is shown by the equation

{ }_{92}^{238} \mathrm{U} \rightarrow{ }_{90}^{234} \mathrm{Th}+\mathrm{X} .

For nucleus X , calculate the ratio, in $\mathrm{Ckg}^{-1}$ , of $\frac{\text { charge }}{\text { mass }}$ .
ratio = $\mathrm{C} \mathrm{kg}^{-1}$

[ 3 ]

charge =2 e
$\left(=2 \times 1.60 \times 10^{-19} \mathrm{C}\right)$
mass =4 u
$\left(=4 \times 1.66 \times 10^{-27} \mathrm{~kg}\right)$
ratio $=\left(2 \times 1.60 \times 10^{-19}\right) /\left(4 \times 1.66 \times 10^{-27}\right)$ $=4.8 \times 10^{7} \mathrm{C} \mathrm{~kg}^{-1}$

(c)

Two particles P and Q each consist of three quarks. These quarks are up (u) or down (d) quarks.

Particle P has no overall charge.
Particle Q has an overall charge of +2 e, where e is the elementary charge.
State the quark composition of:

[ 2 ]

(i)

particle P

[ 1 ]

(ii)

particle Q.

[ 1 ]

[Maximum number: 1]

The table lists the nucleon number and the proton number of various nuclei. The nuclei are represented by the letters L to T.

Table for Question 3 — CAIE A-Level Physics AS

Which row in the following table correctly shows three nuclei of the same element, and three nuclei that have the same number of neutrons?

same element

same number

of neutrons

LM N

RPN

MPS

RST

OPQ

MPS

RPN

OPQ

All question bank results loaded

Covered syllabus points

Question 1

Question 2

Question (a)

Question (b)

Question (c)

Question (i)

Question (ii)

Question 3