Exploring Radiation and Decay Processes

Which of the following is NOT a type of ionising radiation?

• Alpha

• Beta

• Gamma

• Infrared

Answer explanation

Infrared is not a type of ionising radiation. Ionising radiation includes alpha, beta, and gamma rays, which have enough energy to remove tightly bound electrons from atoms.

What is the main difference between alpha and beta decay?

• Alpha decay emits electrons, beta decay emits helium nuclei

• Alpha decay emits helium nuclei, beta decay emits electrons or positrons

• Both emit the same particles

• Beta decay emits protons, alpha decay emits neutrons

Answer explanation

The correct choice states that alpha decay emits helium nuclei, while beta decay emits electrons or positrons. This distinction is crucial in understanding the types of radiation produced during these decay processes.

What is the half-life of a radioactive substance?

• The time it takes for all atoms to decay

• The time it takes for half the atoms to decay

• The time it takes for the substance to become non-radioactive

• The time it takes for the temperature to halve

Answer explanation

The half-life of a radioactive substance is defined as the time it takes for half the atoms to decay. This means that after one half-life, only half of the original amount of the substance remains.

Which of the following particles has the greatest mass?

• Alpha particle

• Beta particle

• Gamma ray

• Neutrino

Answer explanation

The alpha particle, consisting of 2 protons and 2 neutrons, has a greater mass than the beta particle (an electron), gamma ray (a photon), and neutrino (very light particle). Thus, the alpha particle has the greatest mass.

Which type of radiation is most easily stopped by a sheet of paper?

• Alpha

• Beta

• Gamma

• X-ray

Answer explanation

Alpha radiation consists of heavy particles that can be easily stopped by a sheet of paper, making it the least penetrating type of radiation compared to beta, gamma, and X-ray radiation.

• A proton

• An electron

• A neutron

• A positron

Answer explanation

During beta minus (\beta^-) decay, a neutron in the nucleus transforms into a proton, emitting an electron and an antineutrino. Therefore, the correct answer is 'An electron', which is emitted in this process.

Which of the following is a property of gamma rays?

• They have mass

• They are highly ionising

• They are electromagnetic waves

• They are stopped by paper

Answer explanation

Gamma rays are a form of electromagnetic radiation, meaning they are waves of energy without mass. They are not highly ionising compared to alpha and beta particles, and they can penetrate materials much more than paper.

If a radioactive sample has a half-life of 4 hours, how much of the original sample remains after 8 hours?

• All of it

• Half

• One quarter

• One eighth

Answer explanation

After 4 hours, half of the sample remains. After another 4 hours (total 8 hours), half of that remaining sample is left. Thus, 1/2 of 1/2 equals 1/4 of the original sample remains, which is the correct answer.

Which of the following is a common use of gamma radiation?

• Smoke detectors

• Medical imaging and cancer treatment

• Powering watches

• Lighting

Answer explanation

Gamma radiation is commonly used in medical imaging and cancer treatment due to its ability to penetrate tissues and provide detailed images or target cancer cells effectively.

What is the charge of an alpha particle?

• 0

• +1

• +2

• -1

Answer explanation

An alpha particle consists of 2 protons and 2 neutrons, giving it a net positive charge of +2. Therefore, the correct answer is +2.