One atom of an element X weighs 6 × 10^–23 gm. Number of moles of atoms in 3.6 kg of sample of X will
be : (N_A = 6 × 10²³)
 

Atomic weight = weight of an atom x Avogadro number = 6 x 10²³ x 6 x 10^-23 = 36

Number of moles = $\frac{\mathrm{given} \mathrm{mass} \mathrm{in} \mathrm{gms} }{\mathrm{GAW}}$

= $\frac{3.6\times 1000}{36}$= 100