Q18 of 46 Page 1

Give reasons for the following:

(a) Transition metals have high enthalpies of atomization.


(b) Manganese has a lower melting point even though it has a higher number of unpaired electrons for bonding.


(c) Ce4+ is a strong oxidizing agent.


(a) Transition metals have high enthalpies of atomization due to presence of unpaired electrons in (n-1)d orbital which are able to make strong inter atomic metallic bonds.


(b) Manganese has a lower melting point even though it has a higher number of unpaired electrons for bonding. Since, the number of unpaired electron increases, the strength of metallic bond between two metal atoms in the metallic lattice also increases due to which melting point of the metal also increases.


(c) The formation of Ce4+ is favoured by the noble gas configuration of Xe but being a strong oxidant it reverts back to +3 state, oxidizing others and getting itself reduced. The reduction potential is favourable for this which is Ce4+/Ce3+= 1.74V. This reduction potential tells that it can oxidize water into oxygen.


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14

(a) Write the dispersed phase and dispersion medium of butter.

(b) Why does physisorption decrease with increase in temperature?


(c) A colloidal sol is prepared by the given method in figure. What is the charge on AgI colloidal particles formed in the test tube? How is this sol represented?


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Write the principle of the following:

(a) Hydraulic Washing


(b) Chromatography


(c) Froth- floatation process


 19

Write the structure of Monomers used for getting the following polymers:

(a) Novolac


(b) Neoprene


(c) Buna - S


OR


(a) Write one example each of


(i) Cross-linked polymer.


(ii) Natural Polymer


(b) Arrange the following in the increasing order of their intermolecular forces:


Terylene, Buna - N, Polystyrene


(c) Define biodegradable polymers with an example.


 23

(a) Write the product when D - glucose reacts with Br2 (aq).

(b) What type of bonding provides stability to - helix structure of protein?


(c) Name the vitamin whose deficiency causes pernicious anaemia.


OR


Define the following terms:


(a) Invert Sugar


(b) Native Protein


(c) Nucleotide