1
rahul1995 yadav
·2010-03-16 22:42:30
1..i think statement 2 is false
29
govind
·2010-03-17 01:13:16
For the first one..carbon forms a Wurtzrite Structure similar to that of ZnS..so the packing fraction will be greater than 74% ...but the second statement is not a correct explanation of first..so i go with B..
Ans2..i think the answer shud be A,B and C ..
as the carbon atoms occupy the voids so density shud increase..
11
Devil
·2010-03-17 10:29:45
Govind, 2 A) is ok, how do u explain b) & c) ?
29
govind
·2010-03-17 21:17:33
In the second question u can take the case of iron and steel...pure iron is soft and steel is hard..so i took this case for options B and C...not sure of the answers...maybe i am right..
1
Great Dreams
·2010-03-17 22:13:18
@govind its not wurtizite but zinc blende type
and we can compare both structure due their geometry
in diamond C is tetrahedrally surrounded by other C's so is the case ZnS (blende) it is fcc packing with Zn2+ occupying alternate tetrahedral voids
so i think reason is falsese because packing fraction >74%
1
Tapas Gandhi
·2010-03-17 22:24:58
@govind
steel is not a carbide but say cementite Fe3C
@Soumik
WC tungsten carbide is a very hard substance (edited)
WC is an abrasive (editedx2)
so>>>>A,B,C
electrical conductivity remains comparable
29
govind
·2010-03-17 22:37:55
Ya diamond forms ZnS zinc blende structure..but in rare cases forms wutzrite too(dont worry that's an exception)..but why statement 2 is false Tom?
@Tapas..i meant Fe3C only..that's an important component in steel's manufacturing..
1
Tapas Gandhi
·2010-03-17 22:45:52
WURTZITE STRUCTURE (Wikipedia)

The wurtzite group includes: Cadmoselite CdSe, Greenockite CdS, Mátraite ZnS and Rambergite MnS, in addition to wurtzite.
Diamond Lattice
