Which ofthe following is true regarding teflon ?

• It is a linear, unbranched polymer of tetrafluoro ethylene

• It has very high thermal stability

• Polymer molecules are associated by strong dipole-dipole attraction

• All of the above

Cellulose has very high degree of hydrophilicity because of :

• its amorphous nature

• crystalline nature

• presence of excessive voids in solid state

• presence of many hydroxyl groups on the polymer back bone

By adding sodium dodecyl sulphate, during the electrophoresis of proteins, it is possible to :

• determine a protein's isoelectric point

• determine an enzyme's specific activity

• determine the amino acid composition of the protein

• presence a proteins native structure and biological activity

Which of the following aldoses gives an optically active compound upon reaction with warm dilute nitric acid ?

In the $\mathrm{\alpha }$-helix , the hydrogen bonds

• are roughly parallel to the axis of the helix

• are roughly perpendicular to the axis of the helix

• occur mainly between electronegative atoms of the R groups

• occur only between some of the amino acids of the helix

Which one ofthe following antioxidant commonly used to increase the storage life of butter ?

• Butylated hydroxy anisol

• Sodium sulphite

• Sodium metabisulphite

• All of the above

57.

CH₃CHO $\stackrel{\mathrm{Oxidation}}{\to }$ (A0 $\stackrel{{\mathrm{PCl}}_5}{\to }$ (B) $\stackrel{{\mathrm{CH}}_3\mathrm{COONa}}{\to }$ (c) .Compond (C) is :

• (CH₃CO)₂O

• CH₃COCH₃

• CH₃COOCH₃

• CH₃COOC₂H₅

The strongest acid among the following compound is :

• HCOOH

• CH₃CH₂CH(Cl)COOH

• ClCH₂CH₂CH₂COOH

• CH₃COOH

Phenol , when it first react with cone. sulphuric acid and then with cone. nitric acid gives :

• nitrobenzene

• 2 , 4 , 6 - trinitrobenzene

• o - nitrophenol

• p - nitrophenol

During dehydration of alcohols to alkenes by heating with conc. H₂SO₄ , the initial step is :

• formation of an este

• protonation of alcohol molecule

• formation of carbocation

• elimination of water