Find the number of chemical species in which outer shell 'd' orbital is having more than five electrons.
`Ac, Cd, Zn, Sn, Cr, Pt, Ag`

Answer

To solve the question of finding the number of chemical species in which the outer shell 'd' orbital has more than five electrons, we will analyze the given elements: Ac (Actinium), Cd (Cadmium), Zn (Zinc), Sn (Tin), Cr (Chromium), Pt (Platinum), and Ag (Silver).

### Step-by-Step Solution:

1. **Identify the Elements and Their Electron Configurations**:
- **Ac (Actinium)**: [Rn] 6d¹
- **Cd (Cadmium)**: [Kr] 4d¹⁰ 5s²
- **Zn (Zinc)**: [Ar] 3d¹⁰ 4s²
- **Sn (Tin)**: [Kr] 4d¹⁰ 5s² 5p²
- **Cr (Chromium)**: [Ar] 3d⁵ 4s¹
- **Pt (Platinum)**: [Xe] 4f¹⁴ 5d⁹ 6s²
- **Ag (Silver)**: [Kr] 4d¹⁰ 5s¹

2. **Determine the Number of Electrons in the 'd' Orbital**:
- For each element, we focus on the 'd' orbital:
- **Ac**: 1 electron in 'd' (not more than 5)
- **Cd**: 10 electrons in 'd' (more than 5)
- **Zn**: 10 electrons in 'd' (more than 5)
- **Sn**: 10 electrons in 'd' (not applicable, as it's in 'p' block)
- **Cr**: 5 electrons in 'd' (not more than 5)
- **Pt**: 9 electrons in 'd' (more than 5)
- **Ag**: 10 electrons in 'd' (more than 5)

3. **Count the Elements with More than 5 Electrons in the 'd' Orbital**:
- From our analysis, the elements that have more than 5 electrons in their 'd' orbital are:
- **Cd**: 10 electrons
- **Zn**: 10 electrons
- **Pt**: 9 electrons
- **Ag**: 10 electrons

4. **Final Count**:
- The total number of chemical species with more than 5 electrons in the outer 'd' orbital is **4** (Cd, Zn, Pt, Ag).

### Conclusion:
The answer to the question is **4**.

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