Question

Ans??........... .......... ​

Answer 1

Answer:

Coating of Cobalt=0.005cm

It's applied on a total area of 0.5cm^2.

Hence Volume of Cobalt used=0.0025cm^3

Density of Cobalt =8.9 grams/cm^3

Density=mass/volume

hence mass = denisty*Volume

mass of cobalt used=8.9*0.0025

=0.02225 grams

Hence moles of Cobalt used= 0.02225/59

=0.0003771moles

moles=no.of atoms of the substance/avogadro number

no. of atoms of cobalt= 0.0003771*6.022*10^23

=3771*6.022*10^16

=22708.962 *10^16

=2.2708962*10^20

=2.271*10^20 atoms(by rounding off)

Hope it helps you mate