Pls solve this

Q12. In a unit cell containing X2+, Y3+ and Z2– where X2+ occupies 1/8th of tetrahedral voids, Y3+ occupies 1/2 of octahedral voids and Z2– forms ccp structure. Then formula of compound is 

       (1) X2Y4Z                                      (2) XY2Z4

       (3) XY3Z4                                      (4) X4YZ2

Q13. On rising temperature and decreasing pressure in CsCl solid

         (1) C.N, of metal ion increases from 6 to 8.

         (2) Number of formula unit per unit cell (Z) changes from one to four

         (3) Density of unit cell is increased

         (4)  f + f -  (radius ratio) is increased

 

Dear Student,

On increasing the temperature there occurs an decrease in co-ordination number. While, on increasing the pressure there occurs an increase in the co-ordination number. NaCl structure having  6:6 co-ordination number structure , on applying high pressure to it gets converted to CsCl structure which is having  8:8 co-ordination.Thus, there is an increase in the co-ordination number on increasing pressure. If we heat the CsCl structure at high temperature it gets converted to NaCl structure.Thus, there is an decrease in the co-ordination number on increasing the temperature. 
Conversion of one crystalline form to another by varying temperature and/or pressure is called polymorphism.This is shown by compounds having differences in crystal packing.

Regards,

  • -37
What are you looking for?