Lanthanoid form series is

Options

A. La to Lu
B. Th to Lr
C. Ce to Lu
D. Ac to Lr

Answer

To solve the question regarding the lanthanoid series, we can break it down into the following steps:

### Step 1: Identify the Elements in the Lanthanoid Series
The lanthanoid series consists of a group of 15 elements in the f-block of the periodic table. These elements are characterized by the filling of the 4f subshell.

### Step 2: Determine the Starting and Ending Elements
The lanthanoid series starts with Cerium (Ce) and ends with Lutetium (Lu).

### Step 3: Write Down the Atomic Numbers
- Cerium (Ce) has an atomic number of 58.
- Lutetium (Lu) has an atomic number of 71.

### Step 4: List the Elements in the Series
The elements in the lanthanoid series are:
1. Cerium (Ce, 58)
2. Praseodymium (Pr, 59)
3. Neodymium (Nd, 60)
4. Promethium (Pm, 61)
5. Samarium (Sm, 62)
6. Europium (Eu, 63)
7. Gadolinium (Gd, 64)
8. Terbium (Tb, 65)
9. Dysprosium (Dy, 66)
10. Holmium (Ho, 67)
11. Erbium (Er, 68)
12. Thulium (Tm, 69)
13. Ytterbium (Yb, 70)
14. Lutetium (Lu, 71)

### Step 5: Conclusion
Thus, the lanthanoid series is defined as the series of elements from Cerium (Ce) to Lutetium (Lu), or from atomic number 58 to 71.

### Final Answer
The lanthanoid series starts from Cerium (Ce) and ends at Lutetium (Lu), covering atomic numbers 58 to 71.

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