Question

An aluminium rod weighs 3.9 grams. If the atomic mass of Al is 27 u, how many atoms of aluminium are present in it?

Answer 1

Explanation:

Mass of 1 atom of Al = 27 u

Mass of 1 mole of Al = 27 g

Moles of Al in 3.9 g = 3.9/27 moles = 13/90 moles

Atoms of Al = 13/90 × 6.023 × 10²³ atoms

= 8.69 × 10²² atoms