Question
An element crystallises in fcc unit cell with cell edge length of 3.608 10^ -8 cm, the density of element is 8.92 gcm ^ -3 . Calculate the atomic mass of element ( N _A = 6.022 10^ 23 ).
MHT CET
Chemistry
Solid State
2026
MHT CET 2026 (15 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. 60 g/mol
- B. 65 g/mol
- C. 63 g/mol
- D. 108 g/mol
Answer
C. 63 g/mol
Step-by-step solution
For an fcc unit cell, the number of atoms per unit cell is Z = 4. The formula for the density of a unit cell is given by: d = Z M N_A a^3 Rearranging the formula to solve for the atomic mass M: M = d N_A a^3 Z Given values: d = 8.92 g cm ^ -3 N_A = 6.022 10^ 23 mol ^ -1 a = 3.608 10^ -8 cm Substituting the values into the formula: M = 8.92 6.022 10^ 23 (3.608 10^ -8 )^3 4 M = 8.92 6.022 10^ 23 46.97 10^ -24 4 M = 252.3 4 M 63.07 g/mol Rounding to the nearest integer, the atomic mass of the element is 63 g/mol . Answer: 63 g/mol
Related: Chemistry — Solid State · All PYQ Banks