Question

An element having bcc geometry has atomic mass
50. Calculate the density of the unit cell, if its edge
length is 290 pm.
(1) 6.81 g cm
(2) 3.40 g cm
(3) 13.62 g cm 3
(4) 1.23 g cm

Answer 1

Answer:

We know z=2 of ncc. Na(avagadro no.) =6.023 × 10²³

Mass given =0.05 kg. Density(d) =?

Edge length(a) =290 × 10-¹² m

Now use formula d=(molar mass × Z) /a³ × Na

d=0.05 × 2/(290 × 10-¹²) ³ × 6.023 × 10²³

d=6800.8 kg/m³

Or 6.81 g/cm³

Hence option 1 is correct