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# The number average molecular mass and mass average molecular mass of a polymer are respectively 30,000 and 40,000.The polydispersity index of the polymer is

$\begin{array}{1 1}(a)\;< 1&(b)\;> 1\\(c)\;1&(d)\;0\end{array}$

Given :
$\bar{M_w}$ of the polymer =40,000
$\bar{M_N}$ of the polymer =30,000
Poly dispersity index (PDI) of a polymer is
PDI=$\large\frac{\bar{M_w}}{\bar{M_N}}$
$\Rightarrow \large\frac{40000}{30000}$
$\Rightarrow 1.33 > 1$
Hence (b) is the correct answer.