Which of the following properties cannot be predicted from the positions of the elements in the periodic table ?

Options

A. Nature of oxide
B. Formula of a particular compound
C. Total number of isotopes
D. Oxidising or reducing nature

Answer

To determine which property cannot be predicted from the positions of the elements in the periodic table, we will analyze the properties mentioned in the video transcript step by step.

### Step-by-Step Solution:

1. **Understanding the Periodic Table**:
- The periodic table is organized into groups (columns) and periods (rows). There are 18 groups and 7 periods.
- Elements in the same group often exhibit similar chemical properties due to their similar valence electron configurations.

2. **Properties that can be Predicted**:
- **Nature of Oxides**:
- Metals typically form basic oxides, while non-metals form acidic oxides. This can be predicted based on their position in the periodic table.
- **Chemical Formulas of Compounds**:
- The formation of compounds like NaCl can be predicted by understanding the electron configuration of the elements involved (e.g., Na loses one electron and Cl gains one).
- **Oxidizing and Reducing Agents**:
- The nature of an element as an oxidizing or reducing agent can be inferred from its electron configuration and position in the periodic table.

3. **Property that Cannot be Predicted**:
- **Total Number of Isotopes**:
- The number of isotopes of an element (e.g., Carbon has isotopes C-12, C-13, C-14) is not determined by its position in the periodic table. Isotopes are variations of elements with different neutron counts and are not reflected in the periodic table.

### Conclusion:
The property that cannot be predicted from the positions of the elements in the periodic table is the **Total Number of Isotopes**.

### Final Answer:
**The total number of isotopes (Option 3)**.

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