Radioactive Decay

The atomic number represents

• number of protons

• number of neutrons

• number of protons and neutrons

• number of electrons

The mass number is the same as nucleons.

• True

• False

If an atom is radioactive, it will

• undergo a process called spontaneous transmutation

• emit an alpha or beta particle, or gamma radiation

• spontaneously emit radiation from its nucleus

• All of the above

An alpha particle consists of

• two protons and two electrons

• two electrons and two neutrons

• two neutrons and two protons

• two neutrons and two nucleons

A beta-minus particle is

• an electron and neutrino

• an electron

• the result of a proton transmutating into a neutron

• an antineutrino and an electron

A beta-plus particle is

• a positron, a positively charged electron

• a positron, a positively charged neutron

• a neutrino, a negatively charged neutron

• a proton, a positively charged particle

A gamma ray has

• a positive charge

• a negative charge

• no charge

• none of the above

A nuclear reaction is

• A) the same as a chemical reaction

• B) is different to a chemical reaction

• C) conserves atomic and mass numbers

• D) B and C only

Select all that are correct:

• Alpha and beta particles travel at 90% of the speed of light

• Beta particles are much lighter than alpha particles and they have less ionising and penetrating ability compared to alpha particles

• Gamma rays travel at the speed of light and have high penetrating power but low ionising power

• Alpha, beta particles and gamma rays are affected by electric and magnetic fields

If Th-234 has a half-life of 24 days, how many half-lives has Th-234 undergone after 120 days?