20 Radioactivity 2019J IG

Four nuclides are represented.

Which pair of nuclides are isotopes of the same element?

• E and G

• E and L

• G and L

• G and M

A student measures the level of radiation emitted from a radioactive substance. He places a detector very close to the substance. He puts different absorbers between the radioactive substance and the detector.

The student’s results are shown.

These results are corrected for background radiation.

Which types of radiation are being emitted by the substance?

• α-particles and β-particles only

• α-particles and γ-rays only

• β-particles and γ-rays only

• α-particles, β-particles and γ-rays

The nuclei of the atoms in a substance are changing randomly and emitting radiation.

What is happening to the substance?

• It is undergoing electromagnetic induction.

• It is undergoing magnetisation.

• It is undergoing solidification.

• It is undergoing radioactive decay.

A simple model of the atom consists of small particles orbiting a central nucleus. Which row is correct?

Which statement explains the meaning of the half-life of a radioactive isotope?

• half the time taken for one nucleus of the isotope to decay

• half the time taken for the isotope to decay completely

• the time taken for half of the nuclei of the isotope to decay

• the time taken for one nucleus of the isotope to split in half

The diagram shows a lead-lined box used for storing radioactive sources.

Why is the inside of the box lined with lead?

• It helps the sources to stay radioactive for longer.

• It makes the box heavier.

• It makes the radioactive sources more stable.

• It reduces the amount of radiation that can escape from the box.

Which statement about the structure of an atom is correct?

• It contains positively charged particles only.

• It contains negatively charged particles only.

• It contains no charged particles.

• It contains positively charged particles and negatively charged particles.

Which statement about γ-radiation is correct?

• It consists of very small charged particles.

• It is a form of electromagnetic radiation.

• It is less penetrating than β-radiation.

• It is more highly ionising than α-radiation.

A radioactive element undergoes α-decay.

Which statement is not correct?

• A different element is formed.

• Radiation is emitted from the nucleus.

• The decay is a random process.

• The number of particles in the nucleus stays the same.

The chemical symbol for sodium is Na.

The equation represents the radioactive decay of sodium-24.

What are the numbers x and y?

• x = 10, y = 0

• x = 10, y = 1

• x = 12, y = 0

• x = 12, y = 1