Which suggestion, A, B or C, would not reduce the exposure of the teacher to radiation?

Q1. Before using a radioactive source, a teacher asked her students to suggest safety procedures that would reduce her exposure to the radiation. The...
Author: Simon Bond
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Q1.

Before using a radioactive source, a teacher asked her students to suggest safety procedures that would reduce her exposure to the radiation. The students made the following

(a)

Which suggestion, A, B or C, would not reduce the exposure of the teacher to radiation? ........................................................................ (1)

(b)

The diagram shows how the teacher measured the distance that the radiation traveled from the source. The count-rate at different distances from the source was measured and recorded in the table.

Distance from source to Count-rate in counts detector in cm per minute 20

85

40

81

60

58

80

53

100

23

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What type of radiation was the source emitting, alpha, beta or gamma? ..................................................................................................................................... Explain the reasons for your choice. ........................................................................................................ ............................. ............................................................................................................................. ........ ..................................................................................................................................... ............................................................................................................................. ........ (3)

(c)

The graphs show how two groups of scientists, A and B, link exposure to radiation and the risk of getting cancer.

(i)

Complete the following sentence using a word or phrase from the box.

decreases

has no effect on

increases

Both groups of scientists agree that a high level of exposure to radiation ............................................................ the risk of getting cancer. (1)

(ii)

Use the graphs to describe carefully how the two groups of scientists disagree when the level of exposure to radiation is very low. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (Total 7 marks)

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Q2.

Four different processes are described in List A. The names of these processes are given in List B. Draw a line to link each description in List A to its correct name in List B. Draw only four lines.

(Total 4 marks)

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Q3.

Four different processes are described in List A. The names of these processes are given in List B. Draw a line to link each description in List A to its correct name in List B. Draw only four lines. List A

List B ionisation

the nucleus of an atom splitting into several pieces gamma emission the nuclei of two atoms joining together nuclear fission an atom losing an electron

nuclear fusion an electric charge moving through a metal electric current (Total 4 marks)

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Q4.

The diagram shows an atom.

How many protons are there in the nucleus of the atom? ................................................. What is the mass number of the atom? .............................................................................. (Total 2 marks)

Q5.

The diagram shows a helium atom.

(a)

(i)

electron

Use the words in the box to label the diagram. neutron

proton (2)

(ii)

An alpha particle is the same as the nucleus of a helium atom. How is an alpha particle different from a helium atom? ........................................................................................................................... ........................................................................................................................... (1)

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(b)

The graph shows how the count rate from a sample of radioactive sodium-24 changes with time.

(i)

How many hours does it take for the count rate to fall from 100 counts per second to 50 counts per second? Time = .............................. hours (1)

(ii)

What is the half-life of sodium-24? Half-life = .............................. hours (1)

(c)

A smoke detector contains a small amount of americium-241. Americium-241 is a radioactive substance which emits alpha particles. It has a half-life of 432 years. (i)

Which one of the following statements gives a reason why the americium-241 inside the smoke detector will not need replacing? Put a tick ( ) in the box next to your answer.

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The alpha particles have a low energy.

People replace smoke detectors every few years.

Americium-241 has a long half-life. (1)

(ii)

The diagram shows the label on the back of the smoke detector.

Why do people need to know that the smoke detector contains a radioactive material? ........................................................................................................................... ............................................................................................. .............................. (1) (Total 7 marks)

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M1.

(a)

C 1

(b)

beta accept gamma if answer alpha can still gain marks for saying why not beta or gamma 1

any two from: must have at least one quantitative statement to get 2 marks •

range in air for beta is (at least) 50cm



count-rate does not drop (much) in first 40cm



count-rate does not fall much until distance is 60cm



alphas cannot travel more than 5cm in air / alphas could not travel 100cm in air accept alphas cannot travel that far



alphas would not be detected



gammas not absorbed by 100cm of air accept gammas not stopped by air accept gammas travel further than alphas and betas strength of source is neutral references to penetrating power is neutral 2

(c)

(i)

increases 1

(ii)

Group A think that (even a very small level of exposure) gives some risk accept there is always a risk, no matter how small the level of exposure 1

Group B think that there is no risk (from a very low level of exposure) accept below a certain level of exposure there is no risk no marks for a simple graph description 1

[7]

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M2.

four lines correct allow 1 mark for each correct line if more than 1 line is drawn from a box in List A, mark each line incorrect

[4]

M3.

[4]

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M4. •

4



9 each for 1 mark [2]

M5.

(a)

(i)

all 3 labels correct allow 1 mark for 1 correct label 2

(ii)

has no electrons it = alpha allow alpha has a positive(charge) allow a helium (atom) has no (charge) do not accept general properties of alpha do not accept general answers in terms of size / density / mass etc 1

(b)

(i)

15 (hours) accept any answer between 14.8 and 15.2 inclusive 1

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(ii)

15 (hours) or their (b) (i) 1

(c)

(i)

americium-241 has a long half life 1

(ii)

any one from: •

alpha (particles) are harmful to … accept radiation / radioactive material is harmful to … accept specific example of harm eg can cause cancer accept radiation is poisonous if ingested / inhaled do not accept it is poisonous / in case of leakage



so they dispose of it safely / appropriately



so they don’t break it open / open it accept do not touch the radioactive source



so they can make a choice about having a radioactive source (in the house) it = radioactive material 1

[7]

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