KBr crystallises in NaCl type of crystal lattice and its density is 2.75 ~g / cm ^3 . Number of unit cells of KBr present in a 1.00 ~mm ^3 grain of KBr are

Step-by-step solution

In a unit cell of KBr , there are four formula units of KBr therefore, Density ( )= 4 119 6.023 10²³ a^3 =2.75 aligned a^3 & =2.873 10⁻²² ~cm ^3 & =2.778 10⁻¹⁹ ~mm ^3 aligned Number of unit cells per mm ^3= 10¹⁹ 2.873 =3.5 10¹⁸