Concept:Condensation polymerization involves bifunctional monomers reacting stepwise with the elimination of small molecules such as water.
Explanation:Dacron, also called terylene, is a polyester obtained by condensation polymerization.
It is synthesized from ethylene glycol and terephthalic acid.
nHOCH2​CH2​OH+nHOOC−C6​H4​−COOH→Dacron+2nH2​OEach time a monomer unit joins the growing polymer chain, a water molecule is eliminated.
This repeated elimination of small molecules is the defining feature of condensation polymerization.
Now examine the remaining options.
Polythene is prepared by addition polymerization of ethene.
Polyacrylonitrile is prepared by addition polymerization of acrylonitrile.
Teflon is prepared by addition polymerization of tetrafluoroethene.
In addition polymerization, monomers simply add together without eliminating any by-product.
Therefore, Dacron is the only polymer among the given options formed by condensation polymerization.
Answer:Option D: Dacron