A crystalline solid of a pure substance has a face-centred cubic structure with a cell edge of 400 pm. If the density of the substance in the crystal is 8g cm^(-3) , then the number of atoms present in 256 g of the crystal isN xx 10^(24). The value of N is

A crystalline solid of a pure substance has a face-centred cubic struc

1.	A crystalline solid of a pure substance has a face-centred cubic structure with a cell edge of 400 pm. If the density of the substance in the crystal is 8g cm^(-3) , then the number of atoms present in 256 g of the crystal isN xx 10^(24). The value of N is
Answer» Solution :`p ( Z XX M)/( a^(3) xx N_(0) xx 10^(-30)` Where a is in pm and M in g ` Mol^(-1)` ` 8 = ( 4 xx M)/((400)^(3) xx 6 xx 10^(23) xx 10^(-30))) ORM = 76.8` Moles in 256 g = ` 256/76.8 = 3.33` No, of ATOMS= ` 3.33 xx 6 xx 10^(23)` `= 2XX 10^(24)`