Q 7. What is the mass of—
(b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27)?
The atomic mass of Aluminium is 27 u.
Mass of 4 moles of aluminium atoms = 4 x Mass of 1 mole of Al atoms
= 4 x molecular mass of aluminium atoms in grams
= 4 x 27
= 108 g