NEET Chemistry The Solid State Questions Solved

NEET - 2016

Lithium has a bcc structure. Its density is 530 kg m-3 and its atomic mass is 6.94 gmol-1. Calculate the edge length of a unit cell of lithium metal.

(NA=6.02 x1023 mol-1)

(a) 352 pm
(b) 527 pm
(c) 264 pm
(d) 154 pm

 

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Concept Questions :-

Density/Formula/packing fraction/ Semiconductors

(a)

 Given, Li has a bcc structure.Density (ρ) = 530 kg.m-3Atomic mass (M) = 6.94 gmol-1We know that, number (NA) = 6.02 × 1023mol-1We know that, number of atoms per unit cell in bcc (Z) = 2. We have the formula for density,                                         ρ=ZMNAa3Where a= edge-length of a unit cell.or a=ZMρNA3= 2 ×6.94 g mol-10.53 g cm-3× 6.02 × 1023mol-13                         = 4.35 ×10-23cm-33                         = 3.52 × 10-8cm                       a= 352 pm

 

Difficulty Level:

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