Question

An element with molar mass 2.7 × 10^-2 kg/mol. Forms a cubic units cell with edge length of 405 pm. If the density is 2.7 × 10³ kg/m³. Find the nature of a cubic unit cell.

Options

• 2, hcp

• 2, ccp

• 4, ccp

• 4, hcp

Answer 1

4, ccp

Explanation:

The density of unit cell is given by

d = `"ZM"/("N" xx "a"^2)`

`"a"^3 = (405 " pm")^3 = (405 xx 10^-10 " cm")^3`

`2.7 xx 10^3 = ("Z" xx 27)/(6.02 xx 10^23 xx (405 xx 10^-10 " cm")^3)`

Z = 3.99 = 4

Hence, the nature of the cubic cell is ccp.