An element has a body-centred cubic (bbc) structure with a cell edge of 288 pm. The density of the element is `7.2g/cm^3`. How many atoms are present in 208 g of the element?

Explanation

`a=288"pm"=288xx10^(-10)"cm"`
`=2.88xx10^(-8)"cm"`
`=2,d=7.2"g cm"^(-3)`
(for b.c.c. lattice)
Mass of the sample, m = 20 g
If n is the number of atoms in the simple of mass m g then density.
`d=(Zxxm)/(a^(3)xxn)`
(Modified formula)
Number of atom, `n=(Zxxm)/(a^(3)xxd)`
`=(Zxxm)/(a^(3)xxd)`
`=(416xx10^(24))/(23.89xx7.2)=2.42xx10^(24)`