Some data for an experiment is shown in the table 1 : No source 2 : With only source 3 : Paper between source and detector 4 : 3 mm thick aluminium sheet between source and detector 5 : 20 cm thick lead block between source and detector Count rate / counts / min 45 745 622 600 45 Explain what you can conclude from the difference in readings between the columns. Enable Ginger Cannot connect to Ginger Check your internet connection or reload the browser Disable in this text field Rephrase Rephrase current sentence Edit in Ginger ×

When there is no source count rate is 45 counts per min. So, the actual count rate due to source is 745 - 45 = 700 counts per min. α -particles are absorbed easily. They are absorbed by a thin sheet of paper. So the count rate due to the alpha particle is 745 - 622 = 123 counts per min. β - particles can travel easily through paper. But absorbed by a few millimetres of metal such as aluminium. So the count rate due to the beta particles is 622 - 600 = 22 counts per min. Gamma radiation is the most penetrating. It takes several centimetres of a dense material like lead to absorb most of the gamma radiation. So, the count rate due to gamma radiation is 600 .

The table shows the activity of a radioactive sample changed as it decayed. Time / h 0 2 4 6 8 Activity / counts per second 500 280 160 95 55 On the grid, draw a graph of activity against time and use it to deduce the half-life of the substance. Show your method on the graph. The half-life is approximately _ _ _ _ .

The graph between the activity and time is shown below. Half-life is the average time taken for half the atoms in a sample of a radioactive material to decay. Initially, total radioactive substances are 500 atom So From the graph, it will take 2 . 5 h to decay 250 atoms. So the half-life is 2 . 5 hr .

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Earn 100

An isotope of protactinium (symbol $Pa$ ) has $91$ protons and $140$ neutrons in its nucleus. Write the symbol for this nuclide.

Important Questions on Radioactivity

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.2>Q 6

An isotope of protactinium (symbol $Pa$ ) has $91$ protons and $140$ neutrons in its nucleus. The nuclide decays by alpha decay to become an isotope of actinium (symbol $Ac$ ). Write a complete decay equation for this decay.

HARD

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.2>Q 7

{}_{92}^{238}U

decays by alpha decay, then beta decay, then beta decay. Deduce the atomic and mass numbers of the daughter nucleus after the third decay and state the element it has become.

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.3>Q 3

Some data for an experiment is shown in the table

	$1$ : No source	$2 :$ With only source	$3 :$ Paper between source and detector	$4 : 3 mm$ thick aluminium sheet between source and detector	$5 : 20 cm$ thick lead block between source and detector
Count rate $/$ counts $/$ min	$45$	$745$	$622$	$600$	$45$

Explain what you can conclude from the difference in readings between the columns.

EASY

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.4>Q 1

State the radioactive decay.

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.4>Q 2

Describe radioactive decay. In your description, include $:$

The types of decay

Their effect on the parent nucleus

Nuclear equations as appropriate.

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.4>Q 3

A sample of a radioactive substance contains

1000

undecayed atoms. Its half-life is

4.5

years. Calculate the number that will remain undecayed after

9

years.

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.4>Q 4

A radioactive substance has a half-life of $13$ years.

Calculate the time it will take for the number of undecayed atoms in a sample to fall to one-eighth of their original number.

HARD

Upper Secondary-IGCSE

IMPORTANT

Physics for Cambridge IGCSE workbook>Chapter 23 - Radioactivity>Exercise 23.4>Q 5

The table shows the activity of a radioactive sample changed as it decayed.

Time $/$ h	$0$	$2$	$4$	$6$	$8$
Activity $/$ counts per second	$500$	$280$	$160$	$95$	$55$

On the grid, draw a graph of activity against time and use it to deduce the half-life of the substance.

Show your method on the graph.

The half-life is approximately $____$ .

An isotope of protactinium (symbol Pa) has 91 protons and 140 neutrons in its nucleus. Write the symbol for this nuclide.

Important Questions on Radioactivity

Learn and Prepare for any exam you want !

An isotope of protactinium (symbol $Pa$ ) has $91$ protons and $140$ neutrons in its nucleus. Write the symbol for this nuclide.