Neco 2025 Chemistry Question 3

Practice objective / multiple choice question 3 from the 2025 Neco Chemistry examination.

Neco 2025 Chemistry Objective / Multiple Choice Hard Difficulty
Question 3 NECO • 2025 • CHEMISTRY • objective

A polymer is prepared by addition polymerisation of monomer M (molar mass \(M = 100 \; \text{g mol}^{-1}\)). Each polymer chain has two identical end groups, each with a molar mass of \(10 \; \text{g mol}^{-1}\). End‑group analysis shows that the polymer sample contains \(0.020\) mol of end groups. The total mass of the polymer sample is \(5.00\) g. (a) Determine the average degree of polymerisation (\(DP_n\)). (b) Calculate the number‑average molecular weight (\(M_n\)). (c) If the polymer has a polydispersity index of 1.20, find the weight‑average degree of polymerisation (\(DP_w\)).

Answer Options

A. DP_n = 4.80; M_n = 600 g·mol^{-1}; DP_w = 5.76
B. DP_n = 5.00; M_n = 500 g·mol^{-1}; DP_w = 5.76
Correct Answer C. DP_n = 4.80; M_n = 500 g·mol^{-1}; DP_w = 5.76
D. DP_n = 4.80; M_n = 500 g·mol^{-1}; DP_w = 6.00
Correct Answer
C
Correct Option:
DP_n = 4.80; M_n = 500 g·mol^{-1}; DP_w = 5.76

About This Question

This is Neco 2025 Chemistry Question 3. It is one of the objective questions from the 2025 Neco Chemistry examination.

Difficulty level: Hard .

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