Calculate the number of :
(i) molecules [S = 32]
(ii) atoms in 192 g. of sulphur. [S8]

(i) 1 mole of any substance contains 6.023 × 10²³ number of molecules.

S₈ = 8 atoms = 8 × 32 = 256.

256 g S₈ contains = 6.023 × 10²³ number of molecules

So, 192 g will have = 6.023 × 10^{23}\over 256×192

= 192 \over 256 × 6.023 × 10²³

= 0.75 × 6.023 × 10²³ × molecules

(ii) Gram atomic mass of S = 32 g

32 g of S has 6.023 × 10²³ number of atoms

Therefore, 192 g will have

= 6.023 × 10^{23}\over 32×192

= 192 \over 32 × 6.023 × 10²³

= 6 × 6.023 × 10²³ × molecules