How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.0 g ?

Options

A. `2.57 xx 10^(21)`
B. `1.28 xx 10^(21)`
C. `1.71 xx 10^(21)`
D. `5.14 xx 10^(21)`

Answer

A

Explanation

No. of NaCl molecules in a unit cell = 4
Mass of unit cell `= ( 4 xx 58.5)/( 6.022 xx 10^(23))`
No. of unit cells in 1 g
` = ( 1 xx 6.022 xx 10^(23))/( 4 xx 58.5) = 2.57 xx 10^(21)` unit cells