Question

Calculate the number of iron atoms in a piece of iron weighing 2.8g.(atomic mass of iron is 56u)

Answer 1

56 g of iron=6.022×10^23
1g. =6.022×10^23/56
2.8g. =6.022×10^23×2.8/56
=3.011×10^22atom

Answer 2

Given- weigh of iron piece= 2.8g

Avagadro number = 6.022*10^23

Gram mass of iron = 56g

Number of iron atom =

=Given mass /molar mass*avogadro number

= 2.8/56*6.022*10^23

= 3.011*10^23