Question

An element a crystallises in fcc lattice with cell edge of 250pm. calculate density if

Answer 1

here ,
Z= 4 ( contribution of atoms in lattice)
M=??( you have not given me complete question , tell the name of element )
a =250×10^-12 m ( edge length)
N = 6.02 ×10^23 ( avagadro's no.)


apply all values in formula and solve to get answer...

Answer 2

Hey !!

Seems like your question is incomplete !!

Here is the complete question :- An element a crystallises in fcc lattice with cell edge of 250pm. Calculate its density if 250 g of this element contain 2.5 × 10²⁴ atoms.

ANSWER :- In fcc,

         z = 4

        d = (z × M) / a³ × Na ----------------> (i)

No. of atoms = w × M × Na

 = 2.5 × 10²⁴ = 250 g / M × Na

     M = [ 250 × Na ] / 2.5 × 10²⁴  -----------------> (ii)

Putting values of M in equation (i)

d = 4 × 250 g × Na / [2.5 × 10²⁴ atoms × (400 × 10⁻¹⁰ cm³) × Na

      d = 6.25 g/cm³

Good luck !!