# An organs substance (M=169 gram "mol"^(-1)) is dissolved in 2000 "cm^(3) of water. Its osmotic pressure at 12^(@)C was found to be 0*54atm. If

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An organs substance (M=169 gram "mol"^(-1)) is dissolved in 2000 "cm^(3) of water. Its osmotic pressure at 12^(@)C was found to be 0*54atm. If R=0*0821L atm. K^(-1) mol^(-1), calculate the mass of the solute.
Calculate the number of atoms in a unit cell of a metal crystalling in face centered cubic structure.
Distinguish between isothermal process and adiabatic process.
Mention the names of various steps involved in the extraction of pure metals from their ores.

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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.