When `alpha, beta` and `gamma` radiation pass through a gas, their ionizing powers, in decreasing order, are

Options

A. `gamma,alpha,beta`
B. `gamma,beta,alpha`
C. `alpha,beta,gamma`
D. `beta,gamma,alpha`

Answer

To determine the ionizing powers of alpha, beta, and gamma radiation when they pass through a gas, we can analyze the characteristics of each type of radiation.

### Step-by-Step Solution:

1. **Understanding the Types of Radiation**:
- **Alpha Radiation**: Consists of helium nuclei (2 protons and 2 neutrons). They are relatively heavy and positively charged.
- **Beta Radiation**: Consists of electrons (beta-minus) or positrons (beta-plus). They are lighter than alpha particles and carry a single negative or positive charge.
- **Gamma Radiation**: Consists of high-energy photons. They have no mass and no charge.

2. **Ionizing Power**:
- Ionizing power refers to the ability of radiation to ionize atoms or molecules in a medium (in this case, gas). The more ionizing power a radiation has, the more likely it is to collide with and ionize gas molecules.

3. **Comparison of Ionizing Powers**:
- **Alpha Particles**: Due to their larger mass and charge, alpha particles have a high probability of interacting with gas molecules. They can cause significant ionization because they can collide with many gas atoms.
- **Beta Particles**: Beta particles are lighter than alpha particles and have moderate ionizing power. They can ionize gas molecules but not as effectively as alpha particles due to their lower mass and charge.
- **Gamma Rays**: Gamma rays are uncharged and have no mass, which allows them to travel through matter with minimal interaction. As a result, they have the least ionizing power among the three types of radiation.

4. **Arranging in Decreasing Order**:
- Based on the analysis, we can arrange the ionizing powers in decreasing order:
- **Alpha Radiation** (highest ionizing power)
- **Beta Radiation** (moderate ionizing power)
- **Gamma Radiation** (lowest ionizing power)

### Final Answer:
The order of ionizing powers when alpha, beta, and gamma radiation pass through a gas, in decreasing order, is:
**Alpha > Beta > Gamma**.