CAIE IGCSE Physics Nuclear Physics Questions

Practise atomic and nuclear structure, isotope notation, radiation properties, decay, half-life, applications and safety across the Nuclear Physics syllabus.

Covered syllabus points

5.1.1 The atom 5.1.2 The nucleus 5.2.1 Detection of radioactivity 5.2.2 The three types of nuclear emission 5.2.3 Radioactive decay 5.2.4 Half-life 5.2.5 Safety precautions

[Maximum number: 5]

(a)

Describe the structure of an atom of helium- $4,{ }_{2}^{4} \mathrm{He}$ .

[ 3 ]

(b)

The Sun is a medium-sized star powered by nuclear fusion reactions which release energy.

[ 2 ]

(i)

State what happens during nuclear fusion reactions which form helium.

[ 2 ]

[Maximum number: 10]

(a)

State the nature of $\gamma$ -rays.

[ 2 ]

(b)

A nucleus of technetium-99 $\left({ }_{43}^{99} \mathrm{Tc}\right)$ emits only a $\gamma$ -ray.

State any effect of this on

[ 2 ]

(i)

the proton number of the nucleus,

[ 1 ]

(ii)

the nucleon number of the nucleus.

[ 1 ]

(c)

In a laboratory a radiation detector displays a count rate of 16 counts/minute due to background radiation.

[ 4 ]

(i)

State what is meant by background radiation.

[ 1 ]

(ii)

A sample of a radioactive isotope is placed near to the radiation detector and a count rate of 112 counts/minute is recorded.

After 18 hours, the count rate recorded is 28 counts/minute.
Determine the half-life of this isotope.
half-life =

[ 3 ]

112-16 or 96 or 112 / 28 or $\frac{1}{4}$ or 18 / 2

C1

28-16 or 12 or 1 / 8 or 18 / 3 or 9.0 (hours)

C1

6.0 hours

A1

(d)

Radioactive isotopes are stored in thick lead containers.

State two precautions to be taken when radioactive isotopes are used.
1.
2.

[ 2 ]

[Maximum number: 9]

(a)

The chemical symbol of the element lithium is Li . The proton number of lithium is 3 .
Fig. 9.1 is a representation of a nucleus of a radioactive isotope of lithium that is about to decay.

Fig. 9.1

[ 4 ]

(i)

Write down, using nuclide notation, the symbol that represents this isotope of lithium.

[ 1 ]

${ }_{3}^{8}(\mathrm{Li})$

B1

(ii)

This isotope of lithium decays by $\beta$ -particle emission to form another nucleus.

Complete Fig. 9.2 to represent this decay by:
- using the same representation as in Fig. 9.1 and in the space after the arrow, draw a diagram of the nucleus formed by the decay
- writing the name of the particle that is identical to a $\beta$ -particle on the answer line provided.

Fig. 9.2

[ 3 ]

(b)

A radiation detector is set up in a laboratory where there are no radioactive samples.

On six separate occasions, the detector is switched on for 1.0 minute and the background count is recorded. The counts are:

\begin{array}{llllll} 23 & 27 & 25 & 24 & 20 & 25 \end{array}

[ 5 ]

(i)

State why the readings are not all identical.

[ 1 ]

(ii)

Suggest a possible source for this background radiation.

[ 1 ]

(iii)

A sample containing only one radioactive isotope is brought into the laboratory. The half-life of the isotope is 15 hours.

The sample is placed near to the radiation detector in this laboratory. The detector is switched on and, after 1.0 minute, a count of 440 is recorded.

The sample is left next to the detector and the experiment is repeated 45 hours later.
The detector is switched on for 1.0 minute.
Predict the reading for the count obtained on this occasion.
reading

[ 3 ]

440-24 or 416 or 52 or 55 or 79 or 3 (half-lives) or 45 / 15 or $1 / 2^{3}$ or 1 / 8

$1 / 2^{3}$ or 1 / 8 or 52 or 55 or 79

76 (counts)

C1

C1

A1

[Maximum number: 7]

(a)

The arrows in Fig. 11.1 represent the paths of three $\alpha$ -particles moving towards gold nuclei in a thin foil. The gold nuclei are shown as shaded circles.

Fig. 11.1

On Fig. 11.1, complete the paths of the three $\alpha$ -particles.

[ 3 ]

middle: any path to the left within $45^{\circ}$
of horizontal

B1

bottom: path to the right and deflected down ending in a straight line

B1

(b)

Fig. 11.2 shows a geologist holding a radiation detector near a rock.

Fig. 11.2

She holds the detector in a fixed position and records the readings shown in Table 11.1.

Table 11.1

Explain the changes in the detector readings.

[ 2 ]

(c)

A technician is handling a solid radioactive sample that emits $\alpha$ -particles and $\beta$ -particles.

The technician wears thick rubber gloves.
Explain why this may provide some protection from the radiation, but it is not sufficient protection.

[ 2 ]

thick gloves would stop $\alpha /$ alpha (so helpful)

B1

(some) $\beta /$ beta/radiation would penetrate gloves/reach other body parts
(so insufficient protection)

B1

Total:

All question bank results loaded

Covered syllabus points

5. Nuclear physics question 1

Question (a)

Question (b)

Question (i)

5. Nuclear physics question 2

Question (a)

Question (b)

Question (i)

Question (ii)

Question (c)

Question (i)

Question (ii)

Question (d)

5. Nuclear physics question 3

Question (a)

Question (i)

Question (ii)

Question (b)

Question (i)

Question (ii)

Question (iii)

5. Nuclear physics question 4

Question (a)

Question (b)

Question (c)