The penetrating powers of `alpha` and `beta` and `gamma` radiations, 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 penetrating powers of alpha, beta, and gamma radiations in decreasing order, we can follow these steps:

### Step 1: Understand the Types of Radiation
- **Alpha Radiation**: Consists of helium nuclei (2 protons and 2 neutrons), which have a relatively high mass.
- **Beta Radiation**: Consists of electrons (or positrons), which have a much lower mass compared to alpha particles.
- **Gamma Radiation**: Is electromagnetic radiation (photons) with negligible mass.

### Step 2: Compare the Masses
- Alpha particles have the highest mass among the three types of radiation.
- Beta particles (electrons) have a lower mass than alpha particles.
- Gamma rays have no mass at all.

### Step 3: Determine Penetrating Power
- The penetrating power of radiation is inversely related to its mass. This means that the higher the mass, the lower the penetrating power, and vice versa.
- Therefore, since alpha particles are the heaviest, they have the least penetrating power.
- Beta particles, being lighter than alpha particles, have a greater penetrating power than alpha.
- Gamma rays, having negligible mass, have the highest penetrating power.

### Step 4: Write the Decreasing Order
Based on the analysis above, we can conclude the order of penetrating power:
1. **Gamma Radiation** (highest penetrating power)
2. **Beta Radiation**
3. **Alpha Radiation** (lowest penetrating power)

### Final Answer
The penetrating powers of alpha, beta, and gamma radiations in decreasing order are:
**Gamma > Beta > Alpha**