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Question 1

SLPaper 1

Three statements about electrons are:

I. Electrons interact through virtual photons.
II. Electrons interact through gluons.
III. Electrons interact through particles W and Z.

Which statements identify the particles mediating the forces experienced by electrons?

Question 2

HLPaper 1

A pure sample of iodine-131 decays into xenon with a half-life of 8 days.

What is ${\frac{\text{number of iodine atoms remaining}}{\text{number of xenon atoms formed}}}$ after 24 days?

Question 3

SLPaper 1

A graph of the variation of average binding energy per nucleon with nucleon number has a maximum. What is indicated by the region around the maximum?

Question 4

SLPaper 1

Some transitions between the energy states of a particular atom are shown.

Energy transition $E_3$ gives rise to a photon of green light. Which transition will give rise to a photon of longer wavelength?

Question 5

SLPaper 1

Three conservation laws in nuclear reactions are

I. conservation of charge
II. conservation of baryon number
III. conservation of lepton number.

The reaction ${n} \to {\pi^-} + {e^+} + {\bar{v_e}}$ is proposed. Which conservation laws are violated in the proposed reaction?

Question 6

HLPaper 1

What is correct about the Higgs Boson?

Question 7

HLPaper 2

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

${U_{92}^{235}} + {n_{0}^{1}} \rightarrow {Xe_{54}^{140}} + {Sr_{38}^{94}} + 2{n_{0}^{1}}$

Mass of one atom of U-235 $= 235\ u$

Binding energy per nucleon for U-235 $= 7.59\ \text{MeV}$

Binding energy per nucleon for Xe-140 $= 8.29\ \text{MeV}$

Binding energy per nucleon for Sr-94 $= 8.59\ \text{MeV}$

A nuclear power station uses U-235 as fuel. Assume that every fission reaction of U-235 gives rise to $180\ \text{MeV}$ of energy.

A sample of waste produced by the reactor contains $1.0\ \text{kg}$ of strontium-94 (Sr-94). Sr-94 is radioactive and undergoes beta-minus ( $\beta^{-}$ ) decay into a daughter nuclide X. The reaction for this decay is

${Sr_{38}^{94}} \rightarrow X + \bar{v}_e + e$

The graph shows the variation with time of the mass of Sr-94 remaining in the sample.

graph

1.

State what is meant by binding energy of a nucleus.

a(i).

[1]

2.

Outline why quantities such as atomic mass and nuclear binding energy are often expressed in non-SI units. a(ii).

[1]

3.

Show that the energy released in the reaction is about $180 \, \text{MeV}$ . a(iii).

[1]

4.

Estimate, in $J\ kg^{-1}$ , the specific energy of U-235. b(i).

[2]

5.

The power station has a useful power output of $1.2$ GW and an efficiency of $36%$ . Determine the mass of U-235 that undergoes fission in one day.

b(ii).

[2]

6.

The specific energy of fossil fuel is typically $30$ MJ $kg^{-1}$ . Suggest, with reference to your answer to (b)(i), one advantage of U-235 compared with fossil fuels in a power station. b(iii).

[1]

7.

Write down the proton number of nuclide X. c(i).

[1]

8.

State the half-life of ${\text{Sr-94}}$ . c(ii).

[1]

9.

Calculate the mass of Sr-94 remaining in the sample after $10$ minutes. c(iii).

[2]

Question 8

SLPaper 1

The energy-level diagram for an atom that has four energy states is shown.

What is the number of different wavelengths in the emission spectrum of this atom?

Question 9

SLPaper 1

As quarks separate from each other within a hadron, the interaction between them becomes larger. What is the nature of this interaction?

Question 10

HLPaper 1

During the nuclear fission of nucleus X into nucleus Y and nucleus Z, energy is released. The binding energies per nucleon of X, Y and Z are $B_X$ , $B_Y$ and $B_Z$ respectively. What is true about the binding energy per nucleon of X, Y and Z?

Topic 7 - Atomic & Nuclear Physics

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