NEET Chemistry The Solid State Questions Solved

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Iron has a body centred cubic unit cell with a cell edge of 286.65 pm. The density of iron is 

7.87 g cm-3. Use this information to calculate Avogadro's number (At. mass of Fe = 56 g mol-1).

Given :

a = 286.65 pm = 286.65×10-10,

d = 7.87 g cm-3, M = 56 g mol-1

Z = 2            NA = ?

Using formula : d = ZMa3NA or NAZMa3d

or NA2×56(286.65×10-10)3×7.87

or NA112(2.87×10-8)3×7.87

or NA11223.63×7.87×10-24

or NA112185.97×10-24

or NA11218.597 × 1023

 Avogadro's number NA = 6.022×1023

Difficulty Level:

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