MHTCET 22 Apr 2025 Shift 2 Paper

Concept:Polymers formed by condensation of urea and formaldehyde contain $-\mathrm{CO}-\mathrm{NH}-$ (amide) linkages.Explanation:Urea-formaldehyde resin is made by the condensation polymerisation of urea $\left(\mathrm{NH}_2-\mathrm{CO}-\mathrm{NH}_2\right)$ with formaldehyde $\left(\mathrm{HCHO}\right)$.During this reaction, the $-\mathrm{NH}_2$ groups of urea react with formaldehyde, and the resulting polymer chain contains repeated $-\mathrm{CO}-\mathrm{NH}-$ linkages.Glyptal is a polyester, Thermocol is polystyrene, and Buna-N is a copolymer of butadiene and acrylonitrile.None of these contain the $-\mathrm{CO}-\mathrm{NH}-$ linkage.Answer:The correct option is D. Urea-formaldehyde resin.