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MHT CET Chemistry Solid State 2026 MHT CET 2026 (18 April Shift 2)

MHT CET Chemistry Question (2026) — Solution

Question

A metal forms fcc structure. Calculate the volume of fcc unit cell in cm ^3 if void volume is 1.66 10^ -23 \ cm ^3.

Options

  1. A. 4.912 10^ -23 \ cm ^3
  2. B. 8.151 10^ -23 \ cm ^3
  3. C. 9.346 10^ -23 \ cm ^3
  4. D. 6.385 10^ -23 \ cm ^3

Answer

D. 6.385 10^ -23 \ cm ^3

Step-by-step solution

For an fcc (face-centered cubic) structure, the packing efficiency is 74\%. The percentage of void volume in the fcc unit cell is 100\% - 74\% = 26\%. Let the total volume of the unit cell be V. Void volume = 0.26 V 0.26 V = 1.66 10^ -23 \ cm ^3 V = 1.66 10^ -23 0.26 \ cm ^3 V = 6.3846 10^ -23 \ cm ^3 6.385 10^ -23 \ cm ^3 Answer: 6.385 10^ -23 \ cm ^3

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