Identify the addition polymer among the following common engineering plastics.

Introduction / Context:
Polymerisation mechanisms are broadly classified as addition (chain-growth) and condensation (step-growth). Recognising examples of each helps predict byproducts, processing routes, and typical properties.

Given Data / Assumptions:

• Polyethylene forms via addition polymerisation of ethylene.
• Nylons (polyamides) form via condensation with elimination of small molecules (e.g., water).
• Bakelite is a condensation thermoset (phenol + formaldehyde).

Concept / Approach:
Addition polymerisation involves repeated addition across unsaturated bonds without byproduct formation. Polyethylene is the archetypal addition polymer formed from ethylene via radical, Ziegler–Natta, or metallocene catalysis. Condensation polymers eliminate small molecules during chain formation, as with polyamides and phenolic resins.

Step-by-Step Solution:
Match each polymer to mechanism: PE → addition; Nylon, Bakelite → condensation.Select polyethylene as the sole addition polymer listed.

Verification / Alternative check:
Introductory polymer chemistry texts classify PE, PP, PS, and PVC as addition polymers.

Why Other Options Are Wrong:
Nylon: condensation via diacid/diamine or lactam ring opening with water byproduct.Bakelite: condensation thermoset; crosslinked network.

Common Pitfalls:
Assuming ring-opening polymerisations are always addition; nylon-6 from caprolactam is often classed as step-growth-like with water participation.

Final Answer:
Polythene (polyethylene)