An element (atomic mass=250 u) crystallizes in a simple cubic. If the density of the unit cell is `7.2 g cm^(-3)`,what is the radius of the element ?

Options

A. `1.93times10^(-3)cm`
B. `1.93times10^(-8) cm`
C. `1.93times10^(-8)Å`
D. `1.93times10^(-8)m`

Answer

B

Explanation

`d=(ZtimesM)/(a^(3)timesN_(0))therefore7.2=(1times250)/(a^(3)times6.02times10^(23))`
or`a^(3)=57.6times10^(-24)`
or`a=3.86times10^(-8)`
For simple cubic, `r=a//2=1.93times10^(-8)` cm