NTA Abhyas JEE Main2020ChemistrySolid StatePractice
How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00 g ?
Options
- A2.57 × 10 21
- B5.14 × 10 21
- C1.28 × 10 21
- D1.71 × 10 21
Correct answer
A. 2.57 × 10 21
Step-by-step solution
∴ Mass of one unit cell = V × d (V is volume, disdensity) = a 3 × d A l s o , d e n s i t y = n × a t . w t . a 3 × a v . no. ∴ Mass of one unit cell = a 3 × n × at .wt . a 3 × av .no . = n × at .wt . av .no . = 4×58 .5 6 .02×10 23 (n = 4 for cubic shape) = 38.87 × 10 - 23 g No .   of   unit   cell   in   1   g   =   1 38 .87   ×   10 23   =   2 .57   ×   10 21