NEET Chemistry The Solid State Questions Solved

BOARD

Niobium crystallizes in body-centred cubic structure. If its density is 8.55 g cm-3, calculate atomic radius of niobium, given its atomic mass 93u.

1.  149 cm

2.  143 ρm

3.  133 ρm

4.  143 cm

Concept Videos :-

#9 | FCC Unit Cell: Packing Fraction
#20 | Rank of HP Unit Cell
#21 | Packing Fraction of HP Unit Cell
#24 | Density of Unit Cell

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors

Given : ρ = 8.55 g cm3,

M = 93 g/mol-1

Z = 2(For bcc)      a = ?

Using formula

a3M×Zρ×N0×10-30

       x = (36.1)13log x = 13log 36.1 = 13×1.1575 = 0.519x = antilog 0.519 = 3.304

 a393g mol-1×28.55 g cm-3×6.022×1023mol-1×10-30

= 3.61×107 = 36.1×106

a = (36.1)1/3 × 102 ρm

 a = 3.304×102 ρm = 330.4 ρm

For bcc r134a = 34×330.4 = 143.1 ρm

Difficulty Level:

  • 71%
  • 30%
Crack NEET with Online Course - Free Trial (Offer Valid Till September 24, 2019)