Topic 5

What is the nucleon number of a nuclide?

• the number of neutrons in the nucleus

• the number of protons in the nucleus

• the number of protons minus the number of neutrons in the nucleus

• the number of protons plus the number of neutrons in the nucleus

A thin sheet of paper is placed between a radioactive source and a radiation detector. The count rate falls to a very low reading.

From this result, which type of radiation is the source emitting?

• α-particles

• β-particles

• γ-rays

• X-rays

In 1986 the Chernobyl nuclear power station in Ukraine suffered a meltdown.

This caused background radiation in many countries, thousands of kilometres from Chernobyl, to increase.

What was transported in the atmosphere to these countries to cause this rise in background radiation?

• α-particles

• β-particles

• γ-rays

• radioactive isotopes

A nuclide of the element iron has the symbol shown.

56

Fe

26

What does a neutral atom of this nuclide contain?

• Protons:26 Neutrons:30 Electrons:26

• Protons:26 Neutrons:56 Electrons:30

• Protons:30 Neutrons:26 Electrons:56

• Protons:56 Neutrons:26 Electrons:30

Which statement about the nuclei of all atoms is correct?

• They all contain electrons.

• They are all always stable.

• They all contain protons and electrons.

• They all have a positive charge.

A radioactive isotope has a half-life of 120 minutes.

It emits radiation at a rate of 100 particles per second.

How long does it take for the rate of emission to fall to 25 particles per second?

• 30 minutes

• 45 minutes

• 90 minutes

• 240 minutes

Why should all radioactive materials be handled carefully?

• They all make anything they touch radioactive.

• They all catch fire very easily.

• They all emit ionising radiation.

• They all have long half-lives.

Which statement about the structure of an atom is correct?

• Negative electrons surround a neutral nucleus.

• Negative electrons surround a positive nucleus.

• Positive electrons surround a neutral nucleus.

• Positive electrons surround a negative nucleus.

What are isotopes of an element?

• atoms of a different element with a different number of neutrons

• atoms of a different element with a different number of protons

• atoms of the same element with a different number of neutrons

• atoms of the same element with a different number of protons

Four students are discussing ideas about radioactive decay.

Which student’s statement is correct?

• When a β-particle is emitted, the nucleus remains unchanged.

• When an α-particle is emitted, the nucleus changes to that of a different element.

• When a γ-ray is emitted, the nucleus changes to that of a different element.

• Stable nuclei are dangerous because they emit high levels of

  γ-radiation.