calculate the ratio of atoms present in 5g of magnesium and 5g of iron...?

(Atomic mass of Mg=24u , Fe=56u )

No. of atoms of Magnesium in 5g of Mg = given mass/molar mass x avogadro no.

 = 5 / 24 x 6.023 x 10^-23 = 0.20 x 6.023 x 10^-23

Similarly no. of atoms of Fe in 5g of Fe  =  5/56 x 6.023 x 10^-23 = 0.08 x 6.023 x 10^-23 

Hence ratio of no. of atoms present in 5 gm of each element,

Mg/ Fe =  0.20 x 6.023 x 10^-23 / 0.08 x 6.023 x 10^-23  

Mg/Fe = 0.20/0.08 =5/2

Hence, Mg : Fe = 5:2