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Aluminium (atomic mass = 24) crystallise...

Aluminium (atomic mass = 24) crystallises in a cube system with edge length of `4Å`. Its density is 2.7 g `cm^(-3)`. The number of aluminium atoms present per unit cell is

A

5

B

6

C

4

D

2

Text Solution

Verified by Experts

The correct Answer is:
C
Given, edge length of cubic system
`=4Å=4xx10^(-8)cm`
density `=2.7 g cm^(-3)" and mass"=27"g/mol"`
So, the number of aluminium atoms present per unit cell
`(Z)=(d xxa^(3)xxN_(A))/(m)`
`=(2.7xx(4xx10^(-8))^(3)xx6.022xx10^(23))/(27)`
`3.85=4`
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