Sodium metal crystallises in body centred cubic lattic with cell edge `4.29 Å` .What is the radius of sodium atom ?

Explanation

In BCC structure
body diagonal `= 4 xx r_(Na) = sqrt3 xx a`
`4 xx r_(Na) = sqrt3 xx 4.29 rArr r_(Na) = (sqrt3)/(4) xx 4.29 = 1.86 Å`