MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The formula for the density of a unit cell is given by: d = Z M N_A a^3 For a bcc unit cell, the number of atoms per unit cell is Z = 2. Given: d = 3.5\ g cm ^ -3 a = 400\ pm = 4 10^ -8 \ cm N_A = 6.022 10^ 23 \ mol ^ -1 Rearranging the formula to solve for molar mass M: M = d N_A a^3 Z Substituting the given values: M = 3.5 6.022 10^ 23 (4 10^ -8 )^3 2 M = 3.5 6.022 10^ 23 64 10^ -24 2 M = 3.5 6.022 6.4 2 M = 67.4464\ g mol ^ -1 Rounding to one decimal place, M 67.4\ g mol ^ -1 . Answer: 67.4\ g mol ^ -1