1.

A metallic element 'X' has cubic lattic. Each edge of the unit cell is 2.0Å and its density is 2.5 g cm^(-3). Number of atoms in 200g of the metal are :

Answer»

`1 xx 10^(20)`
`1 xx 10^(22)`
`1 xx 10^(24)`
`1 xx 10^(25)`

Solution :Volume of unit CELL `= ( 2.0 xx 10^(-8) cm )^(3)`
`= 8 xx 10^(-24) cm^(3)`
Density `= 2.5 g cm^(-3)`
Mass of unit cell `= 8 xx 10^(-24) xx 2.5 `
`= 20 xx 10^(-24) g `
No. of unit cells in 200G`= ( 200)/( 20 xx 10^(-24))`
`= 1 xx 10^( 25)`
Since metallic element has simple cubic lattice, number of atoms in a unit cell =1
No. of atoms in 200g of metal
`=1 xx 10^(25) xx 1 `
`= 1 xx 10^(25) ` atoms


Discussion

No Comment Found

Related InterviewSolutions