Consider the following statements.
I The three series of the transition metals are 3d series (Sc to Zn),4d series (Y to Cd) and 5d series.
II. The two series of the inner transition metals (4f and 5f) are known as actinoids and lanthanoids respectively.
The above mentioned correct statement (s) is /are

Options

A. Only II
B. Only I
C. Both I and II
D. None of these

Answer

To analyze the statements provided in the question, we will break down each statement step by step.

### Step 1: Analyze the First Statement
The first statement claims that the three series of transition metals are the 3d series (Sc to Zn), 4d series (Y to Cd), and 5d series.

- **3d Series:** This series includes elements from Scandium (Sc, atomic number 21) to Zinc (Zn, atomic number 30). This statement is correct.
- **4d Series:** This series includes elements from Yttrium (Y, atomic number 39) to Cadmium (Cd, atomic number 48). This statement is also correct.
- **5d Series:** This series includes elements from Hafnium (Hf, atomic number 72) to Copernicium (Cn, atomic number 112). This statement is correct as well.

**Conclusion for Statement I:** The first statement is correct.

### Step 2: Analyze the Second Statement
The second statement claims that the two series of inner transition metals (4f and 5f) are known as actinoids and lanthanoids respectively.

- **4f Series:** This series includes elements from Lanthanum (La, atomic number 57) to Lutetium (Lu, atomic number 71), and these are known as Lanthanoids. This part of the statement is correct.
- **5f Series:** This series includes elements from Actinium (Ac, atomic number 89) to Lawrencium (Lr, atomic number 103), and these are known as Actinoids. This part of the statement is also correct.

**Conclusion for Statement II:** The second statement is incorrect because it incorrectly states that actinoids correspond to the 4f series and lanthanoids correspond to the 5f series.

### Final Conclusion
- **Statement I is correct.**
- **Statement II is incorrect.**

Thus, the correct answer to the question is that only the first statement is correct.

### Final Answer:
The above-mentioned correct statement(s) is/are: **Only I.**

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