Atomic Structure - GCSE

What is the half-life of a sample of radioactive material whose activity reduces

to 12.5% of its original activity after 6 days?

• 1 day

• 2 days

• 3 days

• 4 days

Answer explanation

Falling to 12.5% of the original activity means that three half-lives have passed, so if three half-lives is 6 days then 1 half-life is 2 days.

Which of the following is an example of irradiation from an external source?

• A Being exposed to X rays in a hospital

• Breathing in radon gas

• Drinking a liquid that contains a radioactive material

• Having radioactive material present on the skin

Answer explanation

Being exposed to X rays is an example

of irradiation, whereas the other

examples are for contamination.

Which of the following is the correct value for the radius of the atom?

Which of the following statements about the atom is not correct?

• The atom has a positively charge nucleus around which electrons orbit

• Most of the mass of the atom is in the nucleus

• The radius of the nucleus is about 1/10000th that of the radius of the atom

• Electrons that orbit the nucleus all have the same energies

Answer explanation

Electrons that orbit the nucleus have different electron energies and are at

different energy levels.

Which of the following relates to the work of James Chadwick?

• He conducted experiments to provide evidence for the existence of the neutron

• He showed that electrons inhabit different energy levels around the nucleus

• He came up with the idea of the atom being like a ‘plum pudding’

• He fired alpha particles at atoms to show they have a small, positive nucleus

Which of the following statements is correct about atomic models over time?

• The model of the atom hasn’t changed in over 200 years

• The plum pudding model replaced the nuclear model of the atom

• The Bohr model was replaced by the nuclear model of the atom

• New models of the atom are accepted when new evidence proves them to be better

Answer explanation

New models of the atom are accepted

when new evidence proves them to be

better, such as when the nuclear model

replaced the plum pudding model.

Which of the following statements about the activity of a radioactive source is

not true?

• The activity of a source is measured in becquerel, Bq

• Activity is the rate at which an unstable nucleus decays

• The activities of different sources can very from fractions of a second to many years

• The activity of a radioactive source will increase as time passes

Answer explanation

The activity of a radioactive source will

decrease as time passes, not increase, as

more and more of the radioactive

particles are decaying and becoming

stable.

Which of the following statements about nuclear radiation is true?

• The alpha particle is the same as a helium nucleus and has the most mass

• Beta particles are fast moving electrons that will be stopped by thin paper

• The neutron is a charged particle that is emitted from the nucleus

• Gamma radiation is the safest of the four types of nuclear radiation

What is the missing particle, shown by the question mark, in the decay

equation ?

• alpha

• beta

• gamma

• neutron

What is the half life of uranium based on the graph?

• 50

• 4500

• 10

• 9000