Apiece of pencil graphite (made of carbon atoms) has a mass of 0.12 grams. how many moles of carbon atoms are in the lead?

              Moles =  0.01 mol

              Number of Atoms  =  6.022 × 10²¹ Atoms

Data Given:

                  Mass  =  0.12 g

                  M.Mass of Carbon  =  12.01 g.mol⁻¹

Calculating Moles:

As we know,

                                Moles  =  Mass ÷ M.Mass

Putting values,

                                Moles  =  0.12 g ÷ 12.01 g.mol⁻¹

                                Moles  =  0.01 mol

Calculate Number of Atoms as,

                   Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms . mol⁻¹

Solving for Number of Atoms,

                   Number of Atoms  =  Moles × 6.022 × 10²³ Atoms . mol⁻¹

Putting value of Moles,

                   Number of Atoms  =  0.01 mol × 6.022 × 10²³ Atoms . mol⁻¹

                   Number of Atoms =  6.022 × 10²¹ Atoms