Q31 / 160 · TS EAMCET 2023 (13 May Shift 1) · Chemistry

A polymer sample contains 3 molecules of molar mass $10^3, 3$ molecules of molar mass 500 and 4 molecules of molar mass 200 . What is its weight average molecular mass?

  • A
    $530$
  • Correct answer
    B
    $737.7$
  • C
    $834.4$
  • D
    $821.6$

Solution

$\begin{aligned} & \bar{M}_w=\frac{\sum n_i M_i^2}{\sum n_i M_i} \\ & =\frac{\left(3 \times\left(10^3\right)^2\right)+\left(3 \times(500)^2\right)+\left(4 \times(200)^2\right)}{\left(3 \times 10^3\right)+(3 \times 500)+(4 \times 200)} \\ & =737.7\end{aligned}$

Hence, the correct answer is option: 'B'.

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