An element crystallises in a bcc lattice with cell edge of 500 pm . The density of the element is 7.5 ~g ~cm ⁻³ . How many atoms are present in 300 ~g of metal ?

Step-by-step solution

(B) a=500 pm =5 10⁻⁸ ~cm a ³= (5 10⁻⁸ ~cm )³=125 10⁻²⁴ ~cm ³ =7.5 ~g ~cm ⁻³, ~m =300 ~g , n =2( for bcc cell ) = nM a ³ ~N _ A M = a ³ N _ A n M= 7.5 125 10⁻²⁴ 6.022 10²³ 2 =282.3 ~g ~mol ⁻¹282.3 ~g of metal contains 6.022 10²³ atoms 300 ~g of metal contains 6.022 10²³ 300 282.3 =6.399 10²³ atoms 6.4 10²³ atoms