Question

how do the ionizing power and penetrating power of alpha particles compare to other types of radiation?
○ alpha particles have intermediate ionizing power and penetrating power.
○ alpha particles have low ionizing power and high penetrating power.
○ alpha particles have high ionizing power and very low penetrating power.
○ alpha particles have low ionizing power and low penetrating power.
○ alpha particles have high ionizing power and high penetrating power.

Explanation:

To determine the correct answer, we recall the properties of alpha particles: Alpha particles (helium nuclei, \( \alpha = \text{He}^{2+} \)) have a large mass and charge. This large charge means they interact strongly with matter, leading to high ionizing power (they can knock electrons off many atoms/molecules). However, their large mass and charge also mean they lose energy quickly when passing through matter, resulting in very low penetrating power (they can be stopped by a sheet of paper or skin).

Now we analyze the options:

• "Intermediate" is incorrect for both (beta is intermediate).
• "Low ionizing, high penetrating" is wrong (beta has lower ionizing than alpha, higher penetrating than alpha; gamma is high penetrating, low ionizing).
• "High ionizing, very low penetrating" matches alpha's properties.
• "Low ionizing, low penetrating" is wrong (alpha is high ionizing).
• "High ionizing, high penetrating" is wrong (gamma is high penetrating, alpha is not).

Answer:

C. Alpha particles have high ionizing power and very low penetrating power.