Atomic structure: GCSE Combined Science Physics practice questions

Question 1 Hard

Leila measures a count rate of 112 counts per second. The half-life is 3 days. Calculate the count rate after 9 days.

Question 2 Hard

A source has a half-life of 11 hours. Its count rate is 80 counts per second. Calculate the count rate 33 hours later.

Question 3 Hard

A source has a half-life of 2 hours. Its count rate is 104 counts per second. Calculate the count rate 6 hours later.

Question 4 Hard

A source has a half-life of 4 minutes. Its count rate is 72 counts per second. Calculate the count rate 12 minutes later.

Question 5 Hard

What is the typical radius of an atom in nanometres?

Question 6 Hard

What is emitted from the nucleus in beta-plus decay, besides a neutron being formed?

Check 1

Where is almost all of the mass of an atom found?

1. In the nucleus.
2. In the electron shells.
3. Spread evenly through the atom.

Check 2

What charge does a neutron have?

1. Positive.
2. None. It is neutral.
3. Negative.

Check 3

A neutral atom has 9 protons. How many electrons has it?

1. 0
2. 18
3. 9

Check 4

What is the proton number of an atom?

1. The number of protons in its nucleus.
2. The number of protons plus neutrons.
3. The number of electron shells.

Check 5

What is the mass number of an atom?

1. The number of protons only.
2. The number of protons plus neutrons.
3. The number of neutrons only.

Check 6

An atom has mass number 14 and 6 protons. How many neutrons?

1. 8
2. 20
3. 6

Check 7

What is an isotope?

1. An atom with a different number of protons.
2. An atom that has lost an electron.
3. An atom of an element with a different number of neutrons.

Check 8

What is an ion?

1. An atom with extra neutrons.
2. An atom that has gained or lost electrons.
3. An atom with extra protons.

Check 9

What is radioactive decay?

1. An unstable nucleus gives out radiation to become more stable.
2. An atom gaining extra electrons.
3. A nucleus joining with another nucleus.

Check 10

What does ionising radiation do to atoms?

1. It adds neutrons to them.
2. It makes them heavier.
3. It knocks electrons off them.

Check 11

What is an alpha particle made of?

1. A fast-moving electron.
2. 2 protons and 2 neutrons.
3. An electromagnetic wave.

Check 12

Which radiation is an electromagnetic wave?

1. Alpha radiation.
2. Beta radiation.
3. Gamma radiation.

Check 13

Which radiation is stopped by a few millimetres of aluminium but not by paper?

1. Beta radiation.
2. Alpha radiation.
3. Gamma radiation.

Check 14

Which radiation is the most strongly ionising?

1. Gamma radiation.
2. Alpha radiation.
3. Beta radiation.

Check 15

What happens to the mass number and proton number in alpha decay?

1. Mass number down by 4, proton number down by 2.
2. Mass number down by 2, proton number down by 4.
3. Mass number unchanged, proton number up by 1.

Check 16

What happens to the proton number in beta decay?

1. It goes down by 1.
2. It goes down by 2.
3. It goes up by 1.

Check 17

Radium-226 has 88 protons and emits an alpha particle. How many protons does the new nucleus have?

1. 84
2. 86
3. 90

Check 18

What is the unit of activity, one decay per second?

1. The becquerel, Bq.
2. The joule, J.
3. The watt, W.

Check 19

What is the half-life of a radioactive source?

1. The time for all the nuclei to decay.
2. Half the time it takes to be safe.
3. The time for the count rate or number of unstable nuclei to halve.

Check 20

A source has a half-life of 4 days. How many half-lives pass in 12 days?

1. 3
2. 48
3. 8

Check 21

A count rate is 48 counts per second. What is it after 2 half-lives?

1. 24 counts per second
2. 12 counts per second
3. 6 counts per second

Check 22

What is the difference between irradiation and contamination?

1. Irradiation is exposure from outside. Contamination is radioactive atoms on or in you.
2. Irradiation is atoms inside you. Contamination is from outside.
3. They mean the same thing.

Check 23

Why does a medical tracer have a short half-life?

1. So it lasts for months inside the body.
2. So it gives out alpha particles.
3. So it soon stops being radioactive in the patient.

Check 24

Someone says all of a source is gone after 2 half-lives. What is wrong?

1. Nothing. Two half-lives is the full life of a source.
2. A quarter is left, because each half-life only halves what remains.
3. Half is left, because 2 half-lives is the same as 1.

Check 25

What was the plum pudding model of the atom?

1. A tiny positive nucleus with electrons orbiting it.
2. A solid sphere that cannot be divided.
3. A ball of positive charge with electrons embedded in it.

Check 26

In the alpha particle scattering experiment, why did most alpha particles go straight through the foil?

1. The atom is mostly empty space.
2. The atom is a solid ball of positive charge.
3. Alpha particles are too heavy to be affected.

Check 27

Why did a few alpha particles bounce back in the scattering experiment?

1. They hit the electrons.
2. They were repelled by a tiny, heavy, positive nucleus.
3. They were attracted to the nucleus.

Check 28

What did Niels Bohr add to the nuclear model of the atom?

1. The nucleus is made of protons and neutrons.
2. The atom is a ball of positive charge.
3. Electrons orbit at specific distances.

Check 29

Whose experiments provided the evidence for the neutron?

1. James Chadwick
2. Niels Bohr
3. J. J. Thomson

Check 30

What happens to an electron when an atom absorbs electromagnetic radiation?

1. It moves to a lower energy level.
2. It moves to a higher energy level.
3. It leaves the nucleus.

Check 31

What happens when an electron falls to a lower energy level?

1. The atom absorbs electromagnetic radiation.
2. The nucleus decays.
3. It gives out electromagnetic radiation.

Check 32

How does an atom become a positive ion?

1. It loses one or more outer electrons.
2. It gains a proton.
3. It gains an electron.

Check 33

Which symbols show an alpha particle and a beta particle in a nuclear equation?

1. Alpha is ⁰₋₁e and beta is ⁴₂He.
2. Alpha is ⁴₂He and beta is ⁰₋₁e.
3. Alpha is ¹₁H and beta is ⁴₂He.

Check 34

Is the nuclear equation ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He balanced?

1. No, because the proton numbers differ.
2. No, because the mass numbers differ.
3. Yes, because 222 + 4 = 226 and 86 + 2 = 88.

Check 35

What does gamma emission do to the mass and charge of a nucleus?

1. Neither changes.
2. The mass falls by 4.
3. The charge rises by 1.

Check 36

Why must studies into the effects of radiation on people be published?

1. So that the scientists become famous.
2. So other scientists can check the findings.
3. So that nobody else can repeat the work.

Check 37

Higher tier. A count rate falls to one eighth of its start. How many half-lives is that, and what is the ratio?

1. 8 half-lives, 8 : 1
2. 4 half-lives, 16 : 1
3. 3 half-lives, 8 : 1

Check 38

What is a positron?

Check 39

What happens in beta-plus decay?

Check 40

What happens in beta-minus decay?

Check 41

What is the radius of an atom?