Total number of elements of 5th period which have one or more than one 5d electrons :-

Options

A. 10
B. 16
C. 30
D. Zero

Answer

To determine the total number of elements in the 5th period that have one or more than one 5d electrons, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the 5th Period Elements**:
The 5th period of the periodic table includes elements with atomic numbers from 37 (Rubidium, Rb) to 48 (Cadmium, Cd). This period contains a total of 12 elements.

2. **Understand the Electron Configuration**:
The elements in the 5th period can be categorized based on their electron configurations. The filling of the d orbitals occurs after the s orbitals of the same period. For the 5th period, the 4d subshell is filled before the 5d subshell.

3. **Identify the d Block Elements**:
The d block elements in the 5th period are those that correspond to the 4d series. These include:
- Yttrium (Y, atomic number 39)
- Zirconium (Zr, atomic number 40)
- Niobium (Nb, atomic number 41)
- Molybdenum (Mo, atomic number 42)
- Technetium (Tc, atomic number 43)
- Ruthenium (Ru, atomic number 44)
- Rhodium (Rh, atomic number 45)
- Palladium (Pd, atomic number 46)
- Silver (Ag, atomic number 47)
- Cadmium (Cd, atomic number 48)

4. **Determine the Presence of 5d Electrons**:
In the 5th period, the 5d subshell does not start filling until the 6th period. Therefore, there are no elements in the 5th period that have electrons in the 5d subshell.

5. **Conclusion**:
Since there are no elements in the 5th period with one or more than one 5d electrons, the total number of elements with 5d electrons is zero.

### Final Answer:
The total number of elements in the 5th period that have one or more than one 5d electrons is **0**.