Q19 of 37 Page 1

Write the structures of the monomers used for getting the following polymers : (i) Dacron (ii) Melamine – formaldehyde polymer (iii) Buna-N

Dacron : dacron is prepared by a condensation reaction between dimethylterephthalate and ethylene glycol in presence of a catalyst consisting of mixture of zinc acetate and antimony trioxide at temperature 425-475K. methanol is eliminated during condensation.


terylene (dacron )


Dimethylterephthalate ethylene glycol


Melamine- formaldehyde polymer


Melamine formaldehyde polymer is manufactured by the condensation polymerisation of melamine and formaldehyde.


melamine formadehyde


copolymer


Melamine formaldehyde


Buna – N


Buna –N is obtained by the copolymerisation of 1, 3 – butadiene and acrylonitrile in the presence of a peroxide catalyst.



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17

A. Write the principle of method used for the refining of germanium.

B. Out of PbS and PbCO3 (ores of lead), which one is concentrated by froth floatation process preferably?


C. What is the significance of leaching in the extraction of aluminimum?

 18

Write structures of compounds A, B and C in each of the following reactions :

A.


B.


Do the following conversions in not more than two steps :


(i) Benzoic acid to benzaldehyde


(ii) Ethyl benzene to Benzoic acid


(iii) Propanone to Propene

 20

Define the following :

(i) Anionic detergents


(ii) Broad spectrum antibiotics


(iii) Antiseptic

 21

Give reasons :

(i) Thermal stability decreases from H2O to H2Te.


(ii) Fluoride ion has higher hydration enthalpy than chloride ion.


(iii) Nitrogen does not form pentahalide.