Starting from radium, the radioactive disintegration process terminates when the following is obtained:

Options

A. Lead
B. Radon
C. Radium A
D. Radium B

Answer

To solve the question regarding the radioactive disintegration process starting from radium, we will follow these steps:

### Step 1: Understand Radioactive Disintegration
Radioactive disintegration is a process where unstable nuclei decay into more stable forms. This process continues until a stable nucleus is formed.

**Hint:** Remember that the goal of radioactive decay is to reach a stable state.

### Step 2: Identify the Starting Element
We start with radium (Ra), specifically radium-224 (Ra-224).

**Hint:** Know the specific isotope you are working with, as different isotopes may have different decay paths.

### Step 3: Determine the Decay Path
Radium-224 undergoes alpha decay. In alpha decay, the nucleus emits an alpha particle (which is essentially a helium nucleus), resulting in a new element.

**Hint:** Alpha decay reduces the atomic mass by 4 and the atomic number by 2.

### Step 4: First Decay Step
When radium-224 undergoes alpha decay, it transforms into radon-220 (Rn-220).

**Hint:** Keep track of the changes in atomic mass and atomic number during decay.

### Step 5: Second Decay Step
Radon-220 also undergoes alpha decay, resulting in polonium-216 (Po-216).

**Hint:** Continue to apply the rules of alpha decay to find the next element.

### Step 6: Third Decay Step
Polonium-216 undergoes another alpha decay, leading to lead-212 (Pb-212).

**Hint:** Remember that each decay step results in a new element.

### Step 7: Final Decay Step
Lead-212 is a stable isotope and does not undergo further decay. Therefore, the radioactive disintegration process terminates at lead-212.

**Hint:** Identify which isotopes are stable and which are not; the process stops at stability.

### Conclusion
The radioactive disintegration process starting from radium terminates when lead-212 (Pb-212) is obtained, as it is the stable nucleus.

**Final Answer:** Lead-212 (Pb-212)