solid

iron crystallizes in fcc lattice

20 Answers

3
msp ·

a,b sure for the post no 3.

1
JOHNCENA IS BACK ·

????????????????

1
JOHNCENA IS BACK ·

REMAINING QUESTIONS...........PLZ TRY N HELP!!!!!!!!!!

1
JOHNCENA IS BACK ·

for #4

i found same question in two different sources...............one says A and other C

1
JOHNCENA IS BACK ·

but for post 2 ans. is given as a

try other questions too!!!!!!

3
msp ·

yes u were rite,i revised long before jee

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JOHNCENA IS BACK ·

msp

don't u think for post 2 it shud be a,c,d

3
msp ·

hey wat do u think abt my suggestion.have i blabberd.pls tell me so that i can delete the post to avoid confusion.

3
msp ·

yes for post no 2.

3
msp ·

noo i think this diag will help u .

see the unit cell and the unit cell is formd by 14 atoms with some void.

1
JOHNCENA IS BACK ·

are compounds containin f-centres paramegnatic usually?

106
Asish Mahapatra ·

yes sankara: but does one corner atom lie completely in the unit cell?

3
msp ·

asish is not rite.he has calculated the the effective no of atoms in a unit cell.

Actually the qn is how many atoms were in the unit cell

106
Asish Mahapatra ·

#2.
f-centres means there is electron present (free electrons) hence they are unpaired and hence paramagnetic

1
JOHNCENA IS BACK ·

:( same here ..............ans. given is c

106
Asish Mahapatra ·

#4:

In simple cubic, there are only 8 corner atoms whose contribution is 1/8 each (they are shared by 8 such adjacent unit cells)
Hence no. of atoms = 8*1/8 = 1

In fcc, there are 8 corner cells whose contribution is 1. The face centres are 6 which are shared by two unit cells hence there contribution is 6*1/2 = 3 so total = 4

In bcc, there are 8 corner cells whose contribution is 1. The body centre is shared by no other unit cell hence its contribution is 1. So no of atoms = 2

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