What are homologous series of carbon compounds ? Write the molecular formula of two consecuative members of homologous series of aldehydes. State which part of these compounds determines their (i) physical and (ii) chemical properties.

Explanation

### Step-by-Step Solution:

1. **Definition of Homologous Series**:
- A homologous series is a group of organic compounds that have the same functional group and similar chemical properties, where each successive member differs from the previous one by a CH₂ unit.

2. **Examples of Aldehydes**:
- The two consecutive members of the homologous series of aldehydes are:
- **Methanal (Formaldehyde)**: Molecular formula is CH₂O.
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