How many of the following is formed by condensation polymerisation?
(I) Nylon-6,6
(II) Terylene
(III) Bakelite

Explanation

To determine how many of the given substances are formed by condensation polymerization, we will analyze each one individually.

### Step 1: Analyze Nylon-6,6
- **Formation**: Nylon-6,6 is formed from hexamethylenediamine and adipic acid.
- **Reaction**: The reaction involves the amine group (-NH2) of hexamethylenediamine reacting with the carboxylic acid group (-COOH) of adipic acid.
- **Byproduct**: During this reaction, a molecule of water (H2O) is released.
- **Conclusion**: Since water is released during the formation of Nylon-6,6, it is formed by condensation polymerization.

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