Molecular weight of PVC: given a degree of polymerisation (DP) of 800, estimate the polymer molecular weight (use 62.5 g/mol per repeat unit).

Introduction / Context:
For vinyl polymers such as PVC, an approximate molecular weight can be estimated by multiplying the degree of polymerisation (number of repeat units) by the molar mass of the repeat unit.

Given Data / Assumptions:

• Repeat unit of PVC (–CH2–CHCl–) ≈ 62.5 g/mol.
• Degree of polymerisation, DP = 800.
• Neglect end-group contributions.

Concept / Approach:
M ≈ DP * M_repeat. This linear estimate is commonly used for quick calculations when end groups are negligible relative to the chain mass.

Step-by-Step Solution:
M_repeat ≈ 62.5 g/mol.M ≈ 800 * 62.5 = 50,000 g/mol.Round to the nearest option: 50,000.

Verification / Alternative check:
Alternate rounding of atomic weights gives similar values; end-group mass adds negligibly at DP 800.

Why Other Options Are Wrong:
51,600; 49,200; 50,800 arise from using different per-unit masses or arithmetic errors.

Common Pitfalls:
Using monomer mass including vinyl unsaturation instead of the repeat-unit mass; mixing DP with molecular weight distribution metrics (Mn, Mw).

Final Answer:
50,000