The correct sequence of ionization power of alpha particle, gamma ray, and beta particle respectively is

Analyze the question: We need the ionizing power of three types of radiation, listed in this order: alpha, gamma, beta.

Concept: Ionizing power depends on how strongly the radiation interacts with atoms in the material it passes through.

• Alpha particle (helium nucleus): Heavy, with a +2 charge and slow speed. It interacts strongly with atoms and strips electrons easily, so its ionizing power is high. Its penetrating power is low, and paper stops it.
• Beta particle (fast electron): Light, with a -1 charge and high speed. Its ionizing power is medium. Its penetrating power is medium, and a few mm of aluminium stops it.
• Gamma ray (electromagnetic wave): It has no charge and no mass, so it rarely interacts with atoms. Its ionizing power is low. Its penetrating power is very high, and thick lead or concrete is needed to reduce it.

Solution: Ionizing power: alpha > beta > gamma.

In the order requested (alpha, gamma, beta):

• Alpha: high
• Gamma: low
• Beta: medium

This gives high, low, medium, which matches option D.

Answer: D. high, low, medium.

Exam tip: Ionizing power and penetrating power are opposites. Remember "A-B-G" for ionizing power going from highest to lowest (Alpha, Beta, Gamma), and "G-B-A" for penetrating power. Also, read the order in the question carefully, because here the options list gamma before beta.