Răspuns:
M(K) = 39 g/mol
n = m/M = 80/39 = 2, 05 moli K
n = 2,05 × 6,022 ₓ 10²³ atomi
= 12,3451 ₓ 10²³ atomi
= 1,23451 ₓ 10²⁴ atomi