NEET Practice Questions (MCQs) with Answers & Solutions

(a) Natural silk contains nitrogen while artificial silk is not.

 It is neoprene rubber.

(d) Ethene, propene and styrene are olefins.

(b) PTFE is teflon; teflon is a polymer of F₂C=CF₂.

(a) PDI abbreviates as polydispersity index of polymer.

    $$\begin{gathered} \mathrm{PDI}=\frac{{\overline{\mathrm{M}}}_{\mathrm{w}}}{{\overline{\mathrm{M}}}_{\mathrm{n}}} \\ \mathrm{For} \mathrm{natural} \mathrm{polymers} \mathrm{PDI} = \mathrm{i}.\mathrm{e}., {\overline{\mathrm{M}}}_{\mathrm{w}}={\overline{\mathrm{M}}}_{\mathrm{n}} \\ \mathrm{For} \mathrm{synthetic} \mathrm{polymers} \mathrm{PDI} > 1, \mathrm{i}.\mathrm{e}., {\overline{\mathrm{M}}}_{\mathrm{w}} > {\overline{\mathrm{M}}}_{\mathrm{n}} \end{gathered}$$

(c) PDI abbreviatives as polydispersity index of polymer.

           PDI = $\frac{{{\displaystyle \stackrel{-}{\mathrm{M}}}}_{\mathrm{w}}}{{{\displaystyle \stackrel{-}{\mathrm{M}}}}_{\mathrm{n}}}$

For natural polymers PDI = i.e, ${\stackrel{\mathrm{\_}}{\mathrm{M}}}_{\mathrm{w}}={\stackrel{\mathrm{\_}}{\mathrm{M}}}_{\mathrm{n}}$

For synthetic polymers PDI > 1, i.e, ${\stackrel{\mathrm{\_}}{\mathrm{M}}}_{\mathrm{w}}>{\stackrel{\mathrm{\_}}{\mathrm{M}}}_{\mathrm{n}}$

(a) Bakelite is stepgrowth polymer, i.e., the condensation involving the reaction of functional group, e.g., terylene, bakelite, etc.

(b) Nylon-6 is a condensation polymer of caprolactam.