Chemistry-2000 -Set II

Q.1 Write the name and molecular structures of the monomers of the following polymers :
(i) Natural Rubber
(ii) Nylon-66

Ans1. (i) Natural rubber monomer is :
CH3 = CH – CH = CH2
|
CH3 2-methyle-1,3-butadiene (Isoprene)
(ii) Monomers of nylon – 66 are :
H2N-(CH2)6 – NH2 (HexamethyleneDiamine) and HOOC-(CH2)4- COOH(adipic acid)

Q.2 (a) Write a chemical equations and reaction conditions for the conversion of :
(i) Ethene to ethanol
(ii) Phenol to phenyl ethanol
(iii) Ethanol to 2-propanol
(b) Give an for each of the following reactions :
(i) Kolbe’s reaction
(ii) Reimer – Tiemann reaction.
…………………………………………H2SO4

Ans2. (a) (i) CH2 = CH2 + H2O ————–> CH3-CH2 – OH

(ii)
——————————————–H3+O
(iii) CH3CHO + CH3MgBr ———————-> CH3-CH-CH3
………………………………………………………………|
……………………………………………………………OH

(b) Kolbe’s Reaction :

(c) Reimer-Timen reaction :

Q.3 (a) Account for the following observation :
(i) Berillium resembles Aluminium in several properties
(ii) The +2 oxidation state of lead is more satable than the +2 oxidation state of tin.
(iii) CO2 is a gas but SiO2 is a solid.
(iv) Hydrogen fluoride has heigher boiling point than hydrogen chloride.
(b) drow the structure of XeF4 molecule. (atomic number Xe = 54)

Ans3. (i) Be and Al are palced diagonally to each other in adjacent groups. The diagonally placed elements show resemblance to each other because of almost similar atomic parameters.
(ii) Pb is more stable in +2 because of inert pair effect.
(iii) CO2 exists as discrete molecules having weak forces of attraction amongest molecules. O = C = O
Unlike ‘C’ , Si acn not form p- p bonds and completes its tetracovalancy by forming a three dimensional network of covalent bonds resulting into the formation of a giant network solid.
(iv) H-F has higher boiling point because of association of molecules through intermolecular H- bonds.

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