Which of the following is the wrong statement?

Options

A. All the actinide elements are radioactive
B. Alkali and alkaline earth metals are s-block elements
C. Chalcogens and halogens are p-block elements
D. The first member of the lanthanide series is lanthanum

Explanation

To determine which of the statements is wrong, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** All the actinide elements are radioactive.

**Analysis:**
Actinides are elements with atomic numbers from 89 (actinium) to 103 (lawrencium). All actinides are indeed radioactive due to their nuclear instability, and they release energy upon radioactive decay.

**Conclusion:** This statement is correct.

### Step 2: Analyze the second statement
**Statement:** Alkali and alkaline earth metals are S-block elements.

**Analysis:**
Alkali metals (Group 1) and alkaline earth metals (Group 2) are classified as S-block elements because their last electron enters the S subshell.

**Conclusion:** This statement is also correct.

### Step 3: Analyze the third statement
**Statement:** Chalcogens and Halogens are p-block elements.

**Analysis:**
Chalcogens (Group 16) and Halogens (Group 17) are indeed p-block elements. In these groups, the last electron enters the p subshell.

**Conclusion:** This statement is correct as well.

### Step 4: Analyze the fourth statement
**Statement:** The first member of the lanthanide series is lanthanum.

**Analysis:**
The lanthanide series consists of elements from lanthanum (La, atomic number 57) to lutetium (Lu, atomic number 71). However, the first member of the series is actually lanthanum itself, but the confusion often arises because cerium (Ce, atomic number 58) is the first f-block element that follows lanthanum in the series.

**Conclusion:** This statement is incorrect in the context of the question, as it suggests that cerium is the first member of the lanthanide series.

### Final Answer
The wrong statement is: **The first member of the lanthanide series is lanthanum.**