Chemistry - Polymer Question with Solution | TestHub

Urea-formaldehyde resin is a condensation polymer formed by the reaction between urea ($\mathrm{N}{\mathrm{H}}_2-\mathrm{CO}-\mathrm{N}{\mathrm{H}}_2$) and formaldehyde ($\mathrm{HCHO}$).

The initial reaction forms methylol urea derivatives, which then undergo condensation with the elimination of water molecules to form a polymer network.

The repeating unit of the resulting polymer chain contains the linkage formed from urea and formaldehyde, which is represented as ${\left[\mathrm{NH}-\mathrm{CO}-\mathrm{NH}-{\mathrm{CH}}_2\right]}_{\mathrm{n}}$.

Other options represent:
${\left[\mathrm{NH}{\left({\mathrm{CH}}_2\right)}_5\mathrm{CO}\right]}_{\mathrm{n}}$ is Nylon-6.
The first image represents polystyrene.
The second image represents polyacrylamide.

Answer: ${\left[\mathrm{NH}-\mathrm{CO}-\mathrm{NH}-{\mathrm{CH}}_2\right]}_{\mathrm{n}}$