Question

Which of the following is the most ionizing radiation?

• A. Alpha
• B. Beta
• C. X rays
• D. Gamma

Hint:

High charge plus large mass equals dense ionization over a very short range.

Answer 1

The Correct Option is A

Step 1: Ionizing power means how much ionization a particle produces per unit path length as it passes through matter. It rises with the particle's charge and mass and falls with its speed.
Step 2: An alpha particle is a helium nucleus with a charge of +2 and a large mass. Because of its high charge and slow speed, it interacts very strongly with electrons in matter and produces dense ionization along a very short track.
Step 3: Compare the others. A beta particle is a single electron with charge of 1 and very small mass, so it ionizes far less. X-rays and gamma rays are uncharged electromagnetic photons that ionize only indirectly and weakly, so their ionizing density is the lowest of the group.
Step 4: The usual ranking of ionizing power is alpha > beta > gamma and X-rays. Note that this is the inverse of penetrating power, where gamma and X-rays travel farthest and alpha is stopped by paper or skin.
Step 5: So the most ionizing radiation is the alpha particle.
Answer: Option A, Alpha.