Calculate the number of particles in each of the following: (a) 46 g of Na atom (b) 8 g of O2 molecules (c) 0.1 moles of carbon atom

(a) No. of moles of sodium = 46/23

= 2 moles

We know that one mole of sodium contains 6.022 x 10²³ atoms.      ∴ 2 moles of sodium contain = 2 x 6.022 x 10²³ atoms

                                                     = 1.204 x 10²⁴ atoms

(b) 1 mole of oxygen = 32 g

32 g of O₂ contains 6.022 x 10²³ molecules

  ∴ 8 g of O₂ contains = (6.022 × 10²³ / 32) x 8 molecules

                                    = 1.51 x 10²³ molecules

(c) 1 mole of carbon atoms contains 6.022 × 10²³ atoms

  ∴ 0.1 mole of carbon atoms contains = 6.022 x 10²³ x 0.1 atoms

                                                                  = 6.022 x 10²² atoms