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प्रश्न
An element crystallizes in a f.c.c. lattice with a cell edge of 250 pm. Calculate the density if 300 g of this element contains 2 × 1024 atoms.
उत्तर
Given: a = 250 pm = 250 × 10−12 m
z = 4
m = 250 × 10-10 cm 2 × 1024 atom weighs = 300g
`m=M/N_A(M" is molar mass")`
`"molar mass, M ="(300xx6.02xx10^23)/(2xx10^24)=90.3" g/mol"`
`"Density, "d=(zM)/(a^3N_A)`
`d=(4xx90.3)/((250)^3xx10^-36xx6.02xx10^23)=38.4" g/cm"^3`
Therefore, the density of the given element is 38.4 g/cm3
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