​In the process of polyesterification, the average length of polymer formed by a stepwise process grows linearly with time. The fraction condensed (extent of reaction) and the degree of polymerization at time t=1 hour, of a polymer formed with $$k_r = 1.80 \times 10^{-2}$$ $$\text{dm}^3\,\text{mol}^{-1}\,\text{s}^{-1}$$ and initial monomer concentration of  $$3.00 \times 10^{-2}$$ $$mol dm^{-3}$$ are respectively

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Correct option is A

​In stepwise polymerization any two monomers present in the reaction mixture can link together at any time and growth of the polymer is not confined to chains that are already forming. As a result, monomers are removed early in the reaction and, as we shall see, the average molar mass of the product grows with time. In chain polymerization an activated monomer, M, attacks another monomer, links to it, then that unit attacks another monomer, and so on. The monomer is used up as it becomes linked to the growing chains. High polymers are formed rapidly and only the yield, not the average molar mass, of the polymer is increased by allowing long reaction times.

The degree of polymerization, which is defined as the average number of monomer residues per polymer molecule. This quantity is the ratio of the initial concentration of A, [A]₀, to the concentration of end groups, [A], at the time of interest, because there is one -A group per polymer molecule. The degree of polymerization (<N>) of a polyesterification reaction time t is given by,

<N>=1+kt[A]₀

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