Which of the following metals is not placed in eighth group of Mendeleev periodic table?

Options

A. Fe
B. Na
C. Pt
D. Ni

Answer

To determine which metal is not placed in the eighth group of Mendeleev's periodic table, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Mendeleev's Periodic Table Structure**:
- Mendeleev's periodic table was organized into groups and periods. The groups represent elements with similar properties.

2. **Identify the Eighth Group**:
- The eighth group in Mendeleev's periodic table includes transition metals. Specifically, it contains three triads of elements.

3. **List the Elements in the Eighth Group**:
- The transition metals in the eighth group include:
- Iron (Fe)
- Cobalt (Co)
- Nickel (Ni)
- Ruthenium (Ru)
- Rhodium (Rh)
- Palladium (Pd)
- Osmium (Os)
- Iridium (Ir)
- Platinum (Pt)

4. **Evaluate the Given Options**:
- The question asks which metal is not in the eighth group. We need to check the options provided (though not listed in the question, we can infer common metals).
- Common metals that might be considered include Sodium (Na), Iron (Fe), Nickel (Ni), and Platinum (Pt).

5. **Identify the Metal Not in the Eighth Group**:
- From the list, Sodium (Na) is not included in the eighth group of Mendeleev's periodic table. It is an alkali metal and belongs to group 1.

6. **Conclusion**:
- Therefore, the metal that is not placed in the eighth group of Mendeleev's periodic table is Sodium (Na).

### Final Answer:
Sodium (Na) is not placed in the eighth group of Mendeleev's periodic table.