`M=169` gm /mol

Vol. of solvent `=200 cm^(3)=2L`

`pi=0-54`

`T=12^(@)C=12+273=285K`

`R=0*0821L atm K^(-) "mol"^(-1)`

`m=?`

`pi V= n RT`

`0*54xx2=(m)/(169)xx0*-082xx285`

`m=(0*54xx2xx169)/(0*082xx285)`

`=(182*52)/(23*37)=7*8g`

No. of atoms situated at 8 corners of unit cell of fcc type

`(1)/(8)xx8=1`

No. of atoms on each sphere

`=(1)/(2)`

Total no. of sphere present in each faces of unit cell

`(1)/(2)xx6=3`

Thus, total spheres present in fcc type `=1+3=4`

Various stpes involved in the extraction of pure metals from their ores are :

(a) Concentration of ores.

(b) Conversion of ores into oxides.

(c) Reduction of ores to form crude metals.

(d) Refining of metals.