Which of the following statement `(s)` is`//`are correct ?

Options

A. Similar electrons configuration is repeated after intervals of `2,8,8`,

`18` and `32` in the extended form of periodic table.
B. In a period from right ot left `(larr)`, reducing nature increases.
C. Along the period `(rarr)` thye number of valency electrons increases from `1` to `8`.
D. The first member of lanthanide series is lanthanum.

Explanation

To determine which of the given statements are correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- The statement claims that "similar electron configuration is repeated after the interval of 2, 8, 8, 18, and 32 in the extended form of the periodic table."
- This is correct. The periodic table is structured such that the electron configurations of elements repeat at these intervals, which correspond to the filling of electron shells.

**Hint:** Look for patterns in electron configurations and the arrangement of elements in the periodic table.

2. **Analyze the Second Statement:**
- The statement says, "in a period from right to left, reducing nature increases."
- This is also correct. As you move from right to left across a period, the elements transition from nonmetals (which tend to gain electrons) to metals (which tend to lose electrons), thus increasing reducing nature.

**Hint:** Consider the properties of metals and nonmetals and how they change across a period.

3. **Analyze the Third Statement:**
- The statement claims, "along the period, the number of valence electrons increases from 1 to 8 as we move from left to right."
- This statement is correct. As you move from left to right across a period, the number of valence electrons increases sequentially from 1 (alkali metals) to 8 (noble gases).

**Hint:** Remember the group number corresponds to the number of valence electrons for main group elements.

4. **Analyze the Fourth Statement:**
- The statement states, "the first member of the lanthanide series is lanthanum."
- This is correct. The lanthanide series indeed starts with lanthanum (La).

**Hint:** Recall the definition of lanthanides and their position in the periodic table.

### Conclusion:
After analyzing all four statements, we find that all of them are correct. Therefore, the answer is that all statements are correct.

### Final Answer:
All statements (1, 2, 3, and 4) are correct.

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