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Atomic Physics

Total questions: 20

Worksheet time: 47mins

Name
Class
Date
1.

A radioactive source emits radiation that can pass through a sheet of paper but not through thick aluminium. What does this show about the radiation?

a)

It is alpha-particles.

b)

It is beta-particles.

c)

It is gamma-rays.

d)

It is a mixture of alpha-particles and gamma-rays

2.

Which line in the table describes the nature of an alpha-particle and a gamma-ray?

a)

A

b)

B

c)

C

d)

D

3.

A radioactive nucleus R decays with the emission of a β-particle as shown:


Which equation is correct?

a)

x = p

b)

y = q

c)

p = x – 1

d)

q = y – 1

4.

How many nucleons are in a nucleus of ?

a)

19

b)

20

c)

39

d)

58

5.

The equation shows the decay of the nuclide X:


What are the values of P and Q ?

a)

A

b)

B

c)

C

d)

D

6.

Which type of radiation has the greatest ionising effect?

a)

α-particles

b)

β-particles

c)

γ-rays

d)

all have the same ionising effect

7.

An unstable nucleus has 145 neutrons and 92 protons. It emits a β-particle.

How many neutrons and protons does the nucleus have after emitting the β-particle?

a)

A

b)

B

c)

C

d)

D

8.

In nuclear ……1……, hydrogen nuclei ……2…… to form helium nuclei, releasing energy.

Which words correctly complete gaps 1 and 2?

a)

A

b)

B

c)

C

d)

D

9.

When Uranium decays it emits an alpha particle, forming an isotope of Thorium. Which of the above decay equations is correct?

a)

A

b)

B

c)

C

d)

D

10.

In the above decay equation, what are the missing numbers x and y?

a)

A

b)

B

c)

C

d)

D

11.

A detector is used to measure the count-rate near a radioactive source. The reading is 4000

counts per minute. After 30 minutes the count-rate has fallen to 500 counts per minute.

What is the half-life of the radioactive source? You may ignore the effects of background

radiation.

a)

3 minutes

b)

5 minutes

c)

6 minutes

d)

10 minutes

12.

The half-life of a radioisotope is 2400 years. The activity of a sample is 720 counts /s.

How long will it take for the activity to fall to 90 counts /s?

a)

300 years

b)

2400 years

c)

7200 years

d)

19 200 years

13.

Americium - 241 has a half life of 400 years. If a sample contains 24 grams starts to decay, after how long will 3 grams be left?

a)

400 yrs

b)

800 yrs

c)

1200 yrs

d)

1600 yrs

14.

The diagram shows a radioactive source, a thick aluminium sheet and a radiation detector.

The radiation detector shows a reading greater than the background reading.

Which type of radiation is being emitted by the source and detected by the detector?

a)

α-radiation

b)

β-radiation

c)

γ-radiation

d)

infra-red radiation

15.

The count rate from a radioactive isotope is recorded every hour. The count rate is corrected forbackground radiation.

The table shows the readings.

What estimate of the half-life of the isotope can be obtained from the readings in the table?

a)

between 1 and 2 hours

b)

between 2 and 3 hours

c)

between 3 and 4 hours

d)

between 4 and 5 hours

16.

BA radioactive source emits three types of radiation R, S and T.

The diagram shows an experiment set up to study the penetrating properties of R, S and T.

a)

A

b)

B

c)

C

d)

D

17.

The graph shows how the count rate on a detector due to a radioactive source changes with time.

What is the count rate at 5.0 hours?

a)

960 counts per minute

b)

600 counts per minute

c)

150 counts per minute

d)

0 counts per minute

18.

A powder contains 400 mg of a radioactive material that emits α-particles.

The half-life of the material is 5 days.

What mass of that material remains after 10 days?

a)

0 mg

b)

40 mg

c)

100 mg

d)

200 mg

19.

The arrangement shown is used to check whether the flour inside a cardboard packet is above a certain level. If it is above this level, the flour absorbs the radiation from the source so that it doesn’t reach the detector.

Which type of radiation is suitable to use?

a)

α-particles only

b)

β-particles only

c)

either α-particles or β-particles

d)

γ-rays only

20.

The half-life of a radioactive substance is 10 minutes. A sample of the radioactive substancecontains 2000 nuclei.

How many radioactive nuclei were in the sample half an hour earlier?

a)

250

b)

4000

c)

6000

d)

16 000